ksh93 is a command and programming language that executes commands read
from a terminal or a file. rksh93 is a restricted version of the
command interpreter ksh93. rksh93 is used to set up login names
and execution environments whose capabilities are more controlled than those
of the standard shell.
See Invocation for the meaning of arguments to the
shell.
A metacharacter is defined as one of the following characters:
; & ( ) | < > NEWLINE SPACE TAB
A blank is a TAB or a SPACE.
An identifier is a sequence of letters, digits, or
underscores starting with a letter or underscore. Identifiers are used as
components of variable names.
A vname is a sequence of one or more identifiers separated
by a period (.) and optionally preceded by a period (.).
vnames are used as function and variable names.
A word is a sequence of characters from the
character set defined by the current locale, excluding non-quoted
metacharacters.
A command is a sequence of characters in the syntax of the
shell language. The shell reads each command and carries out the desired
action either directly or by invoking separate utilities. A built-in command
is a command that is carried out by the shell itself without creating a
separate process. Some commands are built-in purely for convenience and are
not documented in this manual page. Built-ins that cause side effects in the
shell environment and built-ins that are found before performing a path
search (see Execution) are documented in this manual page. For
historical reasons, some of these built-ins behave differently than other
built-ins and are called special built-ins.
A simple-command is a list of variable assignments (see Variable
Assignments) or a sequence of blank-separated words which can be
preceded by a list of variable assignments. See the Environment section
of this manual page.
The first word specifies the name of the command to be executed.
Except as specified in this section, the remaining words are passed as
arguments to the invoked command. The command name is passed as argument 0.
See exec(2). The value of a simple-command is its exit status.
If it terminates normally, its value is 0-255. If it
terminates abnormally, its value is 256+signum. The name of
the signal corresponding to the exit status can be obtained by way of the
-l option of the kill built-in utility.
A pipeline is a sequence of one or more commands separated
by |. The standard output of each command but the last is connected
by a pipe(2) to the standard input of the next command. Each command,
except possibly the last, is run as a separate process. The shell waits for
the last command to terminate. The exit status of a pipeline is the exit
status of the last command unless the pipefail option is enabled.
Each pipeline can be preceded by the reserved word!. This causes the
exit status of the pipeline to become 0 if the exit status of the
last command is non-zero, and 1 if the exit status of the last
command is 0.
A list is a sequence of one or more pipelines separated by
;, &, |&, &&, or |, and optionally terminated
by ;, &, or |&. Of these five symbols, ;,
&, and |& have equal precedence, which is lower than that
of && and ||. The symbols && and
|| also have equal precedence.
A semicolon (;) causes sequential execution of the
preceding pipeline. An ampersand (&) causes asynchronous
execution of the preceding pipeline, that is, the shell does not wait
for that pipeline to finish. The symbol |& causes asynchronous
execution of the preceding pipeline with a two-way pipe established to the
parent shell. The standard input and output of the spawned pipeline can be
written to and read from by the parent shell by applying the redirection
operators <& and >& with arg p to
commands and by using -p option of the built-in commands read
and print. The symbol && (||) causes the
list following it to be executed only if the preceding pipeline
returns a zero (non-zero) value. One or more NEWLINEs can appear in a
list instead of a semicolon, to delimit a command. The first
item of the first pipeline of a list that is a simple
command not beginning with a redirection, and not occurring within a
while, until, or if list , can be preceded by a
semicolon. This semicolon is ignored unless the showme option is
enabled as described with the set built-in.
A command is either a simple-command or one of commands in
the following list. Unless otherwise stated, the value returned by a command
is that of the last simple-command executed in the command.
for vname [ in word ... ] ;do
list ;done
Each time a for command is executed, vname
is set to the next word taken from the in word list. If
in word ... is omitted, the for command executes the
do list once for each positional parameter that is set starting
from 1. Execution ends when there are no more words in the list. See
Parameter Expansion.
for (( [expr1] ; [expr2] ;
[expr3] )) ;do list ;done
The arithmetic expression expr1 is evaluated
first. The arithmetic expression expr2 is repeatedly evaluated until it
evaluates to zero and when non-zero, list is executed and
the arithmetic expression expr3 evaluated. If any expression is
omitted, then it behaves as if it evaluated to 1. See Arithmetic
Evaluation.
select vname [ in word ... ] ;do
list ;done
A select command prints on standard error (file
descriptor 2) the set of words, each preceded by a number. If in
word... is omitted, the positional parameters starting from 1
are used instead. See Parameter Expansion. The PS3 prompt is
printed and a line is read from the standard input. If this line consists of
the number of one of the listed words, then the value of the variable
vname is set to the word corresponding to this number. If this
line is empty, the selection list is printed again. Otherwise the value of the
variable vname is set to null. The contents of the line read
from standard input is saved in the variable REPLY. The list is
executed for each selection until a break or EOF is encountered. If the
REPLY variable is set to null by the execution of list,
the selection list is printed before displaying the PS3 prompt for the
next selection.
case word in [ [(] pattern [ |
pattern ] ... ) list ;; ] ... esac
A
case command executes the
list associated
with the first
pattern that matches
word. The form of the
patterns is the same as that used for file name generation. See
File Name
Generation.
The ;; operator causes execution of case to
terminate. If ;& is used in place of ;; the next
subsequent list, if any, is executed.
if list ;then list [ ;elif
list ;then list ] ... [ ;else list
] ;fi
The list following if is executed and, if
it returns a zero exit status, the list following the first
then is executed. Otherwise, the list following elif is
executed, and, if its value is zero, the list following the next
then is executed. Failing each successive elif list, the
else list is executed. If the if list has
non-zero exit status and there is no else list, then the
if command returns a zero exit status.
while list ;do list ;done
until list ;do list ;done
A while command repeatedly executes the while
list and, if the exit status of the last command in the list is zero,
executes the do list, otherwise the loop terminates. If no
commands in the do list are executed, then the while
command returns a zero exit status, until can be used in place
of while to negate the loop termination test.
((expression))
The expression is evaluated using the rules for
arithmetic evaluation described in this manual page. If the value of the
arithmetic expression is non-zero, the exit status is 0.
Otherwise the exit status is 1.
(list)
Execute list in a separate environment. If two
adjacent open parentheses are needed for nesting, a SPACE must be inserted to
avoid evaluation as an arithmetic command as described in this section.
{ list;}
list is simply executed. Unlike the
metacharacters, ( and ), { and } are reserved
words and must occur at the beginning of a line or after a ; to be
recognized.
[[ expression ]]
Evaluates expression and returns a zero
exit status when expression is true. See Conditional Expressions
for a description of expression.
function varname { list ;}
varname () { list ;}
Define a function which is referenced by
varname.
A function whose
varname contains a dot (
.) is called a
discipline function and the portion of the
varname preceding the last
. must refer to an existing variable.
The body of the function is the list of commands between
{ and }. A function defined with the function varname
syntax can also be used as an argument to the . special built-in
command to get the equivalent behavior as if the varname()
syntax were used to define it. See Functions.
namespace identifier { list
};
Defines or uses the name space identifier and runs
the commands in list in this name space. See Name Spaces.
time [ pipeline ]
If pipeline is omitted, the user and system time
for the current shell and completed child processes is printed on standard
error. Otherwise, pipeline is executed and the elapsed time as well as
the user and system time are printed on standard error. The TIMEFORMAT
variable can be set to a format string that specifies how the timing
information should be displayed. See Shell Variables for a description
of the TIMEFORMAT variable.
The following reserved words are recognized as reserved only when
they are the first word of a command and are not quoted:
case
do
done
else
elif
esac
for
fi
function
if
select
then
time
until
while
{ }
[[ ]]
!
One or more variable assignments can start a simple command or can be arguments
to the typeset, enum, export, or readonly special
built-in commands. The syntax for an assignment is of the form:
varname=word
varname[word]=word
No space is permitted between varname and the
= or between = and word. The variable varname is
unset before the assignment.
varname=(assignlist)
No space is permitted between
varname and the
=. An
assignlist can be one of the following:
word ...
Indexed array assignment.
[word]=word ...
Associative array assignment. If prefixed by
typeset -a, creates an indexed array instead.
assignment ...
Compound variable assignment. This creates a compound
variable varname with sub-variables of the form varname.name,
where name is the name portion of assignment. The value of
varname contains all the assignment elements. Additional assignments
made to sub-variables of varname are also displayed as part of the
value of varname. If no assignments are specified,
varname is a compound variable allowing subsequence child elements to
be defined.
typeset [options] assignment ...
Nested variable assignment. Multiple assignments can be
specified by separating each of them with a ;. The previous value is
unset before the assignment.
. filename
Include the assignment commands contained in
filename.
In addition, a += can be used in place of the = to
signify adding to or appending to the previous value. When += is
applied to an arithmetic type, word is evaluated as an arithmetic
expression and added to the current value. When applied to a string
variable, the value defined by word is appended to the value. For
compound assignments, the previous value is not unset and the new values are
appended to the current ones provided that the types are compatible.
The right hand side of a variable assignment undergoes all the
expansion listed below except word splitting, brace expansion, and file name
generation. When the left hand side is an assignment is a compound variable
and the right hand is the name of a compound variable, the compound variable
on the right will be copied or appended to the compound variable on the
left.
Aliases can be used to redefine built-in commands but cannot be
used to redefine the reserved words listed in the Commands section.
Aliases can be created and listed with the alias command and can be removed
with the unalias command.
Aliasing is performed when scripts are read, not while they are
executed. For an alias to take effect, the alias definition command
has to be executed before the command which references the alias is read.
The following aliases are compiled into the shell but can be unset or
redefined:
autoload='typeset -fu'
command='command '
compound='typeset -C'
fc=hist
float='typeset -lE'
functions='typeset -f'
hash='alias -t --'
history='hist -l'
integer='typeset -li'
nameref='typeset -n'
nohup='nohup '
r='hist -s'
redirect='command exec'
source='command .'
stop='kill -s STOP'
suspend='kill -s STOP $$'
times='{ { time;} 2>&1;}'
type='whence -v'
After alias substitution is performed, each word is checked to see if it begins
with an unquoted tilde (~). For tilde substitution, word also
refers to the word portion of parameter expansion. See Parameter
Expansion.
If it does, the word up to a / is checked to see if it
matches a user name in the password database. If a match is found, the
~ and the matched login name are replaced by the login directory of
the matched user. If no match is found, the original text is left unchanged.
A ~ by itself, or in front of a /, is replaced by
$HOME. A ~ followed by a + or - is replaced by
the value of $PWD and $OLDPWD respectively.
In addition, when expanding a variable assignment, tilde
substitution is attempted when the value of the assignment begins with a
~, and when a ~ appears after a colon (:). The :
also terminates a ~ login name.
The standard output from a command enclosed in parentheses preceded by a dollar
sign ( $(list) ), or in a brace group preceded by a
dollar sign ( ${ list;} ), or in a pair of grave accents
(``) can be used as part or all of a word. Trailing NEWLINEs are
removed. In the second case, the { and } are treated as a
reserved words so that { must be followed by a blank and } must
appear at the beginning of the line or follow a ;. In the third
(obsolete) form, the string between the quotes is processed for special
quoting characters before the command is executed. See Quoting.
The command substitution $(cat file) can be replaced by the
equivalent but faster $(<file). The command substitution
$(n<#) expands to the current byte offset for file
descriptor n. Except for the second form, the command list is run in
a subshell so that no side effects are possible. For the second form, the
final } will be recognized as a reserved word after any token.
An arithmetic expression enclosed in double parentheses preceded by a dollar
sign ( $((arithmetic_expression))) is replaced by the
value of the arithmetic expression within the double parentheses.
Each command argument of the form <(list) or
>(list) runs process list asynchronously
connected to some file in /dev/fd. The name of this file becomes the
argument to the command. If the form with > is selected then writing
on this file provides input for list. If < is used, then the
file passed as an argument contains the output of the list process.
For example,
paste <(cut -f1 file1) <(cut -f3 file2) | tee \
>(process1) >(process2)
cuts fields 1 and 3 from the files file1 and
file2 respectively, pastes the results together, and sends it
to the processes process1 and process2. It also displays the
results to the standard output. The file, which is passed as an argument to
the command, is a UNIX pipe(2). Programs that expect to
lseek(2) on the file do not work.
Process substitution of the form <(list)
can also be used with the < redirection operator which causes the
output of list to be standard input or the input for whatever file
descriptor is specified.
A parameter is a variable, one or more digits, or any of the characters
*, @, #, ?, -, $, and !. A
variable is denoted by a vname. To create a variable whose vname
contains a ., a variable whose vname consists of everything
before the last . must already exist. A variable has a value and zero or more
attributes. Variables can be assigned values and attributes by using the
typeset special built-in command. The attributes supported by the shell
are described later with the typeset special built-in command. Exported
variables pass values and attributes to the environment.
The shell supports both indexed and associative arrays. An element
of an array variable is referenced by a subscript. A subscript for an
indexed array is denoted by an arithmetic expression, (see Arithmetic
Evaluation), between a [ and a ]. To assign values to an
indexed array, use vname=(value ...) or set
-A vname value ... . The value of all subscripts must be in the
range of 0 through 4,194,303. A negative subscript is treated
as an offset from the maximum current index +1 so that -1 refers to the last
element. Indexed arrays can be declared with the -a option to
typeset. Indexed arrays need not be declared. Any reference to a variable
with a valid subscript is legal and an array will be created if
necessary.
An associative array is created with the -A option to
typeset. A subscript for an associative array is denoted by a string
enclosed between [ and ].
Referencing any array without a subscript is equivalent to
referencing the array with subscript 0.
The value of a variable can be assigned by:
vname=value [vname=value] ...
or
vname[subscript]=value [vname[subscript]=value] ...
Note that no space is allowed before or after the =.
Attributes assigned by the typeset special built-in command
apply to all elements of the array. An array element can be a simple
variable, a compound variable or an array variable. An element of an indexed
array can be either an indexed array or an associative array. An element of
an associative array can also be either. To refer to an array element that
is part of an array element, concatenate the subscript in brackets. For
example, to refer to the foobar element of an associative array that
is defined as the third element of the indexed array, use
${vname[3][foobar]}
A nameref is a variable that is a reference to another
variable. A nameref is created with the -n attribute of
typeset. The value of the variable at the time of the typeset
command becomes the variable that is referenced whenever the nameref
variable is used. The name of a nameref cannot contain a dot
(.). When a variable or function name contains a dot (.) and
the portion of the name up to the first . matches the name of a
nameref, the variable referred to is obtained by replacing the
nameref portion with the name of the variable referenced by the
nameref. If a nameref is used as the index of a for
loop, a name reference is established for each item in the list. A
nameref provides a convenient way to refer to the variable inside a
function whose name is passed as an argument to a function. For example, if
the name of a variable is passed as the first argument to a function, the
command
typeset -n var=$1
inside the function causes references and assignments to
var to be references and assignments to the variable whose name has
been passed to the function. If any of the floating point attributes,
-E,-F or -X, or the integer attribute, -i, is
set for vname, then the value is subject to arithmetic
evaluation as described in this manual page. Positional parameters,
parameters denoted by a number, can be assigned values with the set
special built-in command. Parameter $0 is set from argument zero when
the shell is invoked.
The character $ is used to introduce substitutable
parameters.
${parameter}
The shell reads all the characters from ${ to the
matching } as part of the same word even if it contains braces or
metacharacters. The value, if any, of the parameter is substituted. The braces
are required when parameter is followed by a letter, digit, or
underscore that is not to be interpreted as part of its name or when the
variable name contains a dot (.). The braces are also required when a
variable is subscripted unless it is part of an Arithmetic Expression or a
Conditional Expression. If parameter is one or more digits then it is a
positional parameter. A positional parameter of more than one digit must be
enclosed in braces. If parameter is * or @, then all the
positional parameters, starting with $1, are substituted and separated
by a field separator character. If an array vname with last subscript
* or @ is used, or for index arrays of the form sub1
.. sub2 is used, then the value for each of the elements between
sub1 and sub2 inclusive (or all elements for * and
@) is substituted, separated by the first character of the value of
IFS.
${#parameter}
If parameter is * or @, the number
of positional parameters is substituted. Otherwise, the length of the value of
the parameter is substituted.
${#vname[*]}
${#vname[@]}
The number of elements in the array vname is
substituted.
${@vname}
Expands to the type name or attributes of the variable
referred to by vname. See Type Variables.
${!vname}
Expands to the name of the variable referred to by
vname. This is vname except when vname is a name
reference.
${!vname[subscript]}
Expands to name of the subscript unless subscript
is * or @, or of the form sub1 .. sub2.
When subscript is *, the list of array subscripts for
vname is generated. For a variable that is not an array, the value is
0 if the variable is set, otherwise it is null. When
subscript is @, it is the same as $
{vname[*]}, except that when used in double
quotes, each array subscript yields a separate argument. When subscript is of
the form sub1 .. sub2 it expands to the list of
subscripts between sub1 and sub2 inclusive using the same
quoting rules as @.
${!prefix*}
Expands to the names of the variables whose names begin
with prefix.
${parameter:-word}
If parameter is set and is non-null then
substitute its value. Otherwise substitute word.
${parameter:=word}
If parameter is not set or is null, set it
to word. The value of the parameter is then substituted. Positional
parameters cannot be assigned to in this way.
${parameter:?word}
If parameter is set and is non-null, substitute
its value. Otherwise, print word and exit from the shell , if the shell
is not interactive. If word is omitted then a standard message is
printed.
${parameter:+word}
If parameter is set and is non-null, substitute
word. Otherwise substitute nothing.
In the above, word is not evaluated unless it is to be used
as the substituted string. In the following example, pwd is executed
only if d is not set or is NULL:
print ${d:-$(pwd)}
If the colon (:) is omitted from the expression, the shell
only checks whether parameter is set or not.
${parameter:offset:length}
${parameter:offset}
Expands to the portion of the value of
parameter
starting at the character (counting from
0) determined by expanding
offset as an arithmetic expression and consisting of the number of characters
determined by the arithmetic expression defined by
length.
In the second form, the remainder of the value is used. A negative
offset counts backwards from the end of parameter.
One or more BLANKs is required in front of a minus sign to prevent
the shell from interpreting the operator as :-. If parameter is
* or @, or is an array name indexed by * or @,
then offset and length refer to the array index and number of
elements respectively. A negative offset is taken relative to one
greater than the highest subscript for indexed arrays. The order for
associative arrays is unspecified.
${parameter#pattern}
${parameter##pattern}
If the shell pattern matches the beginning of the
value of parameter, then the value of this expansion is the value of
the parameter with the matched portion deleted. Otherwise the value of
this parameter is substituted. In the first form the smallest matching
pattern is deleted and in the second form the largest matching
pattern is deleted. When parameter is @, *, or an
array variable with subscript @ or *, the substring operation is
applied to each element in turn.
${parameter%pattern}
${parameter%%pattern}
If the shell pattern matches the end of the value
of parameter, then the value of this expansion is the value of the
parameter with the matched part deleted. Otherwise substitute the value of
parameter. In the first form the smallest matching pattern is deleted,
and in the second form the largest matching pattern is deleted. When parameter
is @, *, or an array variable with subscript @ or
*, the substring operation is applied to each element in turn.
${parameter/pattern/string}
${parameter//pattern/string}
${parameter/#pattern/string}
${parameter/%pattern/string}
Expands
parameter and replaces the longest match
of
pattern with the specified
string. Each occurrence of
\n in
string is replaced by the portion of
parameter that matches the
nth sub-pattern.
When string is null, the pattern is deleted and the
/ in front of string can be omitted. When parameter is
@, *, or an array variable with subscript @ or
*, the substitution operation is applied to each element in turn. In
this case, the string portion of word is re-evaluated for each
element.
In the first form, only the first occurrence of pattern is
replaced.
In the second form, each match for pattern is replaced by
the specified string.
The third form restricts the pattern match to the beginning of the
string.
The fourth form restricts the pattern match to the end of the
string.
The following parameters are automatically set by the shell:
#
The number of positional parameters in decimal.
-
Options supplied to the shell on invocation or by the
set command.
?
The decimal value returned by the last executed
command.
$
The process number of this shell.
_
Initially, the value of
_ is the absolute pathname
of the shell or script being executed as passed in the environment. It is
subsequently assigned the last argument of the previous command.
This parameter is not set for commands which are asynchronous.
This parameter is also used to hold the name of the matching MAIL
file when checking for mail.
!
The process id or the pool name and job number of the
last background command invoked or the most recent job put in the background
with the bg built-in command. Background jobs started in a named pool
with be in the form pool.number where pool is the pool
name and number is the job number within that pool.
.sh.command
When processing a DEBUG trap, this variable
contains the current command line that is about to run.
.sh.edchar
This variable contains the value of the keyboard
character (or sequence of characters if the first character is an ESC,
ASCII 033) that has been entered when processing a KEYBD trap.
If the value is changed as part of the trap action, then the new value
replaces the key (or key sequence) that caused the trap. See the Key
Bindings section of this manual page.
.sh.edcol
The character position of the cursor at the time of the
most recent KEYBD trap.
.sh.edmode
The value is set to ESC when processing a KEYBD
trap while in vi insert mode. Otherwise, .sh.edmode is null when
processing a KEYBD trap. See the vi Editing Mode section of this
manual page.
.sh.edtext
The characters in the input buffer at the time of the
most recent KEYBD trap. The value is null when not processing a
KEYBD trap.
.sh.file
The pathname of the file than contains the current
command.
.sh.fun
The name of the current function that is being
executed.
.sh.match
An indexed array which stores the most recent match and
sub-pattern matches after conditional pattern matches that match and after
variables expansions using the operators #, %, or /. The
0th element stores the complete match and the ith element stores
the ith sub-match. The .sh.match variable is unset when the
variable that has expanded is assigned a new value.
.sh.math
Used for defining arithmetic functions (see Arithmetic
evaluation) and stores the list of user-defined arithmetic
functions.
.sh.name
Set to the name of the variable at the time that a
discipline function is invoked.
.sh.subscript
Set to the name subscript of the variable at the time
that a discipline function is invoked.
.sh.subshell
The current depth for sub-shells and command
substitution.
.sh.value
Set to the value of the variable at the time that the set
or append discipline function is invoked. When a user-defined arithmetic
function is invoked, the value of .sh.value is saved and
.sh.value is set to long double precision floating point.
.sh.value is restored when the function returns.
.sh.version
Set to a value that identifies the version of this
shell.
LINENO
The current line number within the script or function
being executed.
OLDPWD
The previous working directory set by the cd
command.
OPTARG
The value of the last option argument processed by the
getopts built-in command.
OPTIND
The index of the last option argument processed by the
getopts built-in command.
PPID
The process number of the parent of the shell.
PWD
The present working directory set by the cd
command.
RANDOM
Each time this variable is referenced, a random integer,
uniformly distributed between 0 and 32767, is generated. The
sequence of random numbers can be initialized by assigning a numeric value to
RANDOM.
REPLY
This variable is set by the select statement and
by the read built-in command when no arguments are supplied.
SECONDS
Each time this variable is referenced, the number of
seconds since shell invocation is returned. If this variable is assigned a
value, then the value returned upon reference is the value that was assigned
plus the number of seconds since the assignment.
SHLVL
An integer variable the is incremented each time the
shell is invoked and is exported. If SHLVL is not in the environment
when the shell is invoked, it is set to 1.
The following variables are used by the shell:
CDPATH
Defines the search path for the cd command.
COLUMNS
Defines the width of the edit window for the shell edit
modes and for printing select lists.
EDITOR
If the
VISUAL variable is not set, the value of
this variable is checked for the patterns as described with
VISUAL and
the corresponding editing option is turned on.
See the set command in the Special Command section
of this manual page.
ENV
Performs parameter expansion, command substitution, and
arithmetic substitution on the value to generate the pathname of the script
that is executed when the shell is invoked. This file is typically used for
alias and function definitions. The default value is
$HOME/.kshrc.
See the Invocation section of this manual page.
ENV is not set by the shell.
FCEDIT
Obsolete name for the default editor name for the
hist command.
FCEDIT is not used when
HISTEDIT is set.
The shell specifies a default value to FCEDIT.
FIGNORE
A pattern that defines the set of file names that is
ignored when performing file name matching.
FPATH
The search path for function definitions. The directories
in this path are searched for a file with the same name as the function or
command when a function with the -u attribute is referenced and when a
command is not found. If an executable file with the name of that command is
found, then it is read and executed in the current environment. Unlike
PATH, the current directory must be represented explicitly by dot
(.) rather than by adjacent colon (:) characters or a beginning
or ending colon (:).
HISTCMD
The number of the current command in the history
file.
HISTEDIT
The name for the default editor name for the hist
command.
HISTFILE
If this variable is set when the shell is invoked, the
value is the pathname of the file that is used to store the command history.
See the Command Re-entry section of this manual page.
HISTSIZE
If this variable is set when the shell is invoked, then
the number of previously entered commands that are accessible by this shell is
greater than or equal to this number. The default is 512.
HOME
The default argument (home directory) for the
cd
command.
HOME is not set by the shell. HOME is set by
login(1).
IFS
Internal field separators, normally SPACE, TAB, and
NEWLINE that are used to separate the results of command substitution or
parameter expansion and to separate fields with the built-in command read. The
first character of the
IFS variable is used to separate arguments for
the
"$*" substitution. See the
Quoting section of this
manual page.
Each single occurrence of an IFS character in the string to
be split, that is not in the issspace character class, and any
adjacent characters in IFS that are in the issspace character
class, delimit a field. One or more characters in IFS that belong to the
issspace character class, delimit a field. In addition, if the same
issspace character appears consecutively inside IFS, this
character is treated as if it were not in the issspace class, so that
if IFS consists of two tab characters, then two adjacent tab
characters delimit a null field.
The shell specifies a default value to IFS.
JOBMAX
This variable defines the maximum number running
background jobs that can run at a time. When this limit is reached, the shell
will wait for a job to complete before staring a new job.
LANG
This variable determines the locale category for any
category not specifically selected with a variable starting with LC_ or
LANG.
LC_ALL
This variable overrides the value of the LANG
variable and any other LC_ variable.
LC_COLLATE
This variable determines the locale category for
character collation information.
LC_CTYPE
This variable determines the locale category for
character handling functions. It determines the character classes for pattern
matching. See the File Name Generation section of this manual
page.
LC_NUMERIC
This variable determines the locale category for the
decimal point character.
LINES
If this variable is set, the value is used to determine
the column length for printing select lists. Select lists prints vertically
until about two-thirds of LINES lines are filled.
MAIL
If this variable is set to the name of a mail file
and the
MAILPATH variable is not set, then the shell informs the
user of arrival of mail in the specified file.
MAIL is not set by the shell. On some systems, MAIL
is set by login(1).
MAILCHECK
Specifies how often in seconds the shell checks for
changes in the modification time of any of the files specified by the
MAILPATH or
MAIL variables. The default value is
600
seconds. When the time has elapsed the shell checks before issuing the next
prompt.
The shell specifies a default value to MAILCHECK.
MAILPATH
A colon ( : ) separated list of file names. If
this variable is set, then the shell informs the user of any modifications to
the specified files that have occurred within the last MAILCHECK
seconds. Each file name can be followed by a ? and a message that is
printed. The message undergoes parameter expansion, command substitution, and
arithmetic substitution with the variable $_ defined as the name of the
file that has changed. The default message is you have mail in
$_.
PATH
The search path for commands. Except in
.profile,
users cannot change
PATH if executing under
rksh93. See the
Execution section of this manual page.
The shell specifies a default value to PATH.
PS1
The value of this variable is expanded for parameter
expansion, command substitution, and arithmetic substitution to define the
primary prompt string which by default is
$. The character
! in
the primary prompt string is replaced by the command number. Two successive
occurrences of
! produces a single
! when the prompt string is
printed. See the
Command Re-entry section of this manual page.
The shell specifies a default value to PS1.
PS2
Secondary prompt string, by default,
>.
The shell specifies a default value to PS2.
PS3
Selection prompt string used within a select loop, by
default
#?.
The shell specifies a default value to PS3.
PS4
The value of this variable is expanded for parameter
evaluation, command substitution, and arithmetic substitution and precedes
each line of an execution trace. By default,
PS4 is
+. When
PS4 is unset, the execution trace prompt is also
+ .
The shell specifies a default value to PS4.
SHELL
The pathname of the shell is kept in the environment. At
invocation, if the basename of this variable is
rsh,
rksh,
rksh93, or
krsh, the shell becomes restricted.
SHELL is not set by the shell. On some systems,
SHELL is set by login(1).
TIMEFORMAT
The value of this parameter is used as a format string
specifying how the timing information for pipelines prefixed with the
time reserved word should be displayed. The
% character
introduces a format sequence that is expanded to a time value or other
information.
The format sequences and their meanings are as follows.
%%
A literal %.
%[p][l]R
The elapsed time in seconds.
%[p][l]U
The number of CPU seconds spent in user mode.
%[p][l]S
The number of CPU seconds spent in system mode.
%P
The CPU percentage, computed as (U + S) / R.
The braces denote optional portions. The optional p is a
digit specifying the precision, the number of fractional digits after
a decimal point. A value of 0 causes no decimal point or fraction to
be output. At most three places after the decimal point can be displayed.
Values of p greater than 3 are treated as 3. If
p is not specified, the value 3 is used.
The optional l specifies a longer format, including hours
if greater than zero, minutes, and seconds of the form HHhMMmSS.FFs.
The value of p determines whether or not the fraction is
included.
All other characters are output without change and a trailing
NEWLINE is added. If unset, the default value,
$'\nreal\t%2lR\nuser\t%2lU\nsys%2lS', is used. If the value is null,
no timing information is displayed.
TMOUT
If set to a value greater than zero,
TMOUT is the
default time-out value for the
read built-in command. The
select
compound command terminates after
TMOUT seconds when input is from a
terminal. Otherwise, the shell terminates if a line is not entered within the
prescribed number of seconds while reading from a terminal. The shell can be
compiled with a maximum bound for this value which cannot be exceeded.
The shell specifies a default value to TMOUT.
VISUAL
If the value of this variable matches the pattern
*[Vv][Ii]*, then the vi option is turned on. See Special
Commands. If the value matches the pattern *gmacs* , the
gmacs option is turned on. If the value matches the pattern
*macs*, then the emacs option is turned on. The value of
VISUAL overrides the value of EDITOR.
After parameter expansion and command substitution, the results of substitutions
are scanned for the field separator characters (those found in IFS) and
split into distinct fields where such characters are found. Explicit null
fields ("" or '') are retained. Implicit null fields,
those resulting from parameters that have no values or command substitutions
with no output, are removed.
If the braceexpand (-B) option is set, each of the
fields resulting from IFS are checked to see if they contain one or
more of the brace patterns. Valid brace patterns: {*,*},
{l1..l2} ,
{n1..n2},
{n1..n2%fmt}
{n1..n2 ..n3}, or
{n1..n2
..n3%fmt} , where * represents any
character, l1,l2 are letters and n1,n2,n3
are signed numbers and fmt is a format specified as used by
printf. In each case, fields are created by prepending the characters
before the { and appending the characters after the } to each of the
strings generated by the characters between the { and }. The
resulting fields are checked to see if they have any brace patterns.
In the first form, a field is created for each string between
{ and ,, between , and ,, and between , and
}. The string represented by * can contain embedded matching {
and } without quoting. Otherwise, each { and } with *
must be quoted.
In the second form, l1 and l2 must both be either
upper case or both be lower case characters in the C locale. In this case a
field is created for each character from l1 through l2.
In the remaining forms, a field is created for each number
starting at n1. This continues until it reaches n2 and
increments n1 by n3. The cases where n3 is not
specified behave as if n3 were 1 if n1<=n2,
and -1 otherwise. In forms which specify %fmt, any
format flags, widths and precisions can be specified and fmt can end
in any of the specifiers cdiouxX. For example,
{a,z}{1..5..3%02d}{b..c}x expands to the 8 fields, a01bx,
a01cx, a04bx, a04cx, z01bx, z01cx, z04bx, and z04cx.
Following splitting, each field is scanned for the characters *,
?, (, and [, unless the -f option has been set. If
one of these characters appears, then the word is regarded as a pattern.
Each file name component that contains any pattern character is
replaced with a lexicographically sorted set of names that matches the
pattern from that directory. If no file name is found that matches the
pattern, then that component of the file name is left unchanged unless the
pattern is prefixed with ~(N) in which case it is removed. If
FIGNORE is set, then each file name component that matches the
pattern defined by the value of FIGNORE is ignored when generating
the matching file names. The names . and .. are also ignored.
If FIGNORE is not set, the character . at the start of each
file name component is ignored unless the first character of the pattern
corresponding to this component is the character . itself. For other
uses of pattern matching the / and . are not specially
treated.
*
Match any string, including the null string. When used
for file name expansion, if the globstar option is on, two adjacent
*s by themselves match all files and zero or more directories and
subdirectories. If the two adjacent *s are followed by a /, only
directories and subdirectories match.
?
Matches any single character.
[...]
Match any one of the enclosed characters. A pair of
characters separated by
- matches any character lexically between the
pair, inclusive. If the first character following the opening
[ is a
! or
^, any character not enclosed is matched. A
- can be
included in the character set by putting it as the first or last character.
Within
[ and
], character classes can be specified with the
syntax
[:class:] where
class is one of the
following classes defined in the
ANSI-C standard:
alnum alpha blank cntrl digit graph
lower print punct space upper
word xdigit
word is equivalent to alnum plus the character
_. Within [ and ], an equivalence class can be
specified with the syntax [=c=] which matches all
characters with the same primary collation weight (as defined by the current
locale) as the character c. Within [ and ],
[.symbol.] matches the collating symbol symbol.
A pattern-list is a list of one or more patterns separated
from each other with an & or |. An & signifies
that all patterns must be matched whereas | requires that only one
pattern be matched. Composite patterns can be formed with one or more of the
following sub-patterns:
?(pattern-list)
Optionally matches any one of the specified
patterns.
*(pattern-list)
Matches zero or more occurrences of the specified
patterns.
+(pattern-list)
Matches one or more occurrences of the specified
patterns.
{n(pattern-list)
Matches n occurrences of the specified
patterns.
{m,n(pattern-list)
Matches from m to n occurrences of the
specified patterns. If m is omitted, 0 is used. If n is
omitted at least m occurrences are matched.
@(pattern-list)
Matches exactly one of the specified patterns.
!(pattern-list)
Matches anything except one of the specified
patterns.
By default, each pattern, or sub-pattern matches the longest
string possible consistent with generating the longest overall match. If
more than one match is possible, the one starting closest to the beginning
of the string is chosen. However, for each of the compound patterns a
- can be inserted in front of the ( to cause the shortest
match to the specified pattern-list to be used.
When pattern-list is contained within parentheses, the
backslash character \ is treated specially even when inside a
character class. All ANSI-C character escapes are recognized and
match the specified character. In addition the following escape sequences
are recognized:
\d
Matches any character in the digit class.
\D
Matches any character not in the digit class.
\s
Matches any character in the space class.
\S
Matches any character not in the space class.
\w
Matches any character in the word class.
\W
Matches any character not in the word class.
A pattern of the form %(pattern-pairs) is a
sub-pattern that can be used to match nested character expressions. Each
pattern-pair is a two character sequence which cannot contain
& or |. The first pattern-pair specifies the
starting and ending characters for the match. Each subsequent
pattern-pair represents the beginning and ending characters of a
nested group that is skipped over when counting starting and ending
character matches. The behavior is unspecified when the first character of a
pattern-pair is alphanumeric except for the following:
D
Causes the ending character to terminate the search for
this pattern without finding a match.
E
Causes the ending character to be interpreted as an
escape character.
L
Causes the ending character to be interpreted as a quote
character causing all characters to be ignored when looking for a match.
Q
Causes the ending character to be interpreted as a quote
character causing all characters other than any escape character to be ignored
when looking for a match.
%({}Q"E\), matches characters starting at {
until the matching } is found not counting any { or }
that is inside a double quoted string or preceded by the escape character
\. Without the {} this pattern matches any C language
string.
Each sub-pattern in a composite pattern is numbered, starting at
1, by the location of the ( within the pattern. The sequence
\n, where n is a single digit and \n
comes after the nth. sub-pattern, matches the same string as the
sub-pattern itself.
A pattern can contain sub-patterns of the form
~(options:pattern-list), where either
options or :pattern-list can be omitted. Unlike the
other compound patterns, these sub-patterns are not counted in the numbered
sub-patterns. :pattern-list must be omitted for options F,
G, N and V below. If options is present, it can consist of
one or more of the following:
+
Enable the following options. This is the default.
-
Disable the following options.
E
The remainder of the pattern uses extended regular
expression syntax like the egrep(1) command.
F
The remainder of the pattern uses fgrep(1)
expression syntax.
g
File the longest match (greedy).
This is the default.
G
The remainder of the pattern uses basic regular
expression syntax like the grep(1) command.
i
Treat the match as case insensitive.
K
The remainder of the pattern uses shell pattern syntax.
This is the default.
l
Left anchor the pattern.
This is the default for K style patterns.
N
This is ignored. However, when it is the first letter and
is used with file name generation, and no matches occur, the file pattern
expands to the empty string.
r
Right anchor the pattern.
This is the default for K style patterns.
X
The remainder of the pattern uses augmented regular
expression syntax.
P
The remainder of the pattern uses perl(1) regular
expression syntax. Not all perl regular expression syntax is currently
implemented.
V
The remainder of the pattern uses System V regular
expression syntax.
If both options and :pattern-list are
specified, then the options apply only to pattern-list. Otherwise,
these options remain in effect until they are disabled by a subsequent
~(...) or at the end of the sub-pattern containing ~(...).
Each of the metacharacters listed in the Definitions section of this
manual page has a special meaning to the shell and causes termination of a
word unless quoted. A character can be quoted, that is, made to stand for
itself, by preceding it with a backslash (\). The pair \NEWLINE
is removed. All characters enclosed between a pair of single quote marks
('') that is not preceded by a $ are quoted. A single quote
cannot appear within the single quotes. A single quoted string preceded by an
unquoted $ is processed as an ANSI-C string except for the
following:
\0
Causes the remainder of the string to be ignored.
\cx
Expands to the character CTRL-x.
\C[.name.]
Expands to the collating element name.
\e
Equivalent to the escape character (ASCII
033),
\E
Equivalent to the escape character (ASCII
033),
Inside double quote marks (""), parameter and
command substitution occur and \ quotes the characters \,
`, ", and $. A $ in front of a double
quoted string is ignored in the C or POSIX locale, and might
cause the string to be replaced by a locale specific string otherwise. The
meaning of $* and $@ is identical when not quoted or when used
as a variable assignment value or as a file name. However, when used as a
command argument, "$*" is equivalent to
"$1d$2d...", where d is the first
character of the IFS variable, whereas "$@" is equivalent
to "$1" "$2" .... Inside grave quote marks
(``), \ quotes the characters \, `, and
$. If the grave quotes occur within double quotes, then \ also
quotes the character ".
The special meaning of reserved words or aliases can be removed by
quoting any character of the reserved word. The recognition of function
names or built-in command names cannot be altered by quoting them.
The shell performs arithmetic evaluation for arithmetic substitution, to
evaluate an arithmetic command, to evaluate an indexed array subscript, and to
evaluate arguments to the built-in commands shift and let.
Arithmetic evaluation is also performed on argument operands of the built-in
command printf that correspond to numeric format specifiers in the format
operand. See printf(1). Evaluations are performed using double
precision floating point arithmetic or long double precision floating point
for systems that provide this data type. Floating point constants follow the
ANSI-C programming language floating point conventions. The floating
point constants Nan and Inf can be used to represent "not a
number" and infinity respectively. Integer constants follow the
ANSI-C programming language integer constant conventions although only
single byte character constants are recognized and character casts are not
recognized. Constants can be of the form [base#]n
where base is a decimal number between two and sixty-four representing
the arithmetic base and n is a number in that base. The digits greater
than 9 are represented by the lower case letters, the upper case
letters, @, and _ respectively. For bases less than or equal to
36, upper and lower case characters can be used interchangeably.
An arithmetic expression uses the same syntax, precedence, and
associativity of expression as the C language. All the C language operators
that apply to floating point quantities can be used. In addition, the
operator ** can be used for exponentiation. It has higher precedence
than multiplication and is left associative. When the value of an arithmetic
variable or subexpression can be represented as a long integer, all C
language integer arithmetic operations can be performed. Variables can be
referenced by name within an arithmetic expression without using the
parameter expansion syntax. When a variable is referenced, its value is
evaluated as an arithmetic expression.
Any of the following math library functions that are in the C math
library can be used within an arithmetic expression:
rint round sin sinh sqrt tan tanh tgamma trunc abs acos
acosh asin asinh atan atan2 atanh cbrt ceil copysign cos
cosh erf erfc exp exp2 expm1 fabs fpclassify fdim finite
floor fma fmax fmin fmod hypot ilogb int isfinite sinf isnan
isnormal issubnormal issubor- dered iszero j0 j1 jn lgamma
log log10 log2 logb nearbyint nextafter nexttoward pow
remainder rint round scanb signbit sin sinh sqrt tan tanh
tgamma trunc y0 y1 yn
In addition, arithmetic functions can be defined as shell
functions with a variant of the function name syntax:
function .sh.math.name ident ... {
list ;}
where name is the function name used in the
arithmetic expression and each identified ident is a name reference to
the long double precision floating point argument. The value of
.sh.value when the function returns is the value of this function. User
defined functions can take up to 3 arguments and override C math library
functions.
An internal representation of a variable as a double
precision floating point can be specified with the -E
[n], -F [n], or -X
[n] options of the typeset special built-in
command. The -E option causes the expansion of the value to be
represented using scientific notation when it is expanded. The optional
option argument n defines the number of significant figures. The
-F option causes the expansion to be represented as a floating
decimal number when it is expanded. The optional option argument n
defines the number of places after the decimal point in this case. The
-X option causes the expansion to be represented using the %a
format defined by ISO C-99. The optional option argument n defines the
number of places after the decimal (or radix) point in this case.
An internal integer representation of a variable can be
specified with the -i [n] option of the
typeset special built-in command. The optional option argument
n specifies an arithmetic base to be used when expanding the
variable. If you do not specify an arithmetic base, base 10 is used.
Arithmetic evaluation is performed on the value of each assignment
to a variable with the -E, -F, -X or -i option.
Assigning a floating point number to a variable whose type is an integer
causes the fractional part to be truncated.
When used interactively, the shell prompts with the value of PS1 after
expanding it for parameter expansion, command substitution, and arithmetic
substitution, before reading a command. In addition, each single ! in
the prompt is replaced by the command number. A !! is required to place
! in the prompt. If at any time a NEWLINE is typed and further input is
needed to complete a command, then the secondary prompt, that is, the value of
PS2, is issued.
A conditional expression is used with the [[ compound command to
test attributes of files and to compare strings. Field splitting and file name
generation are not performed on the words between [[ and ]].
Each expression can be constructed from one or more of the
following unary or binary expressions:
-a file
True, if
file exists.
This option is the same as -e. This option is obsolete.
-b file
True, if file exists and is a block special
file.
-c file
True, if file exists and is a character special
file.
-d file
True, if file exists and is a directory.
-e file
True, if file exists.
-f file
True, if file exists and is an ordinary
file.
-g file
True, if file exists and it has its setgid
bit set.
-G file
True, if file exists and its group matches the
effective group id of this process.
-h file
True, if file exists and is a symbolic link.
-k file
True, if file exists and it has its sticky bit
set.
-L file
True, if file exists and is a symbolic link.
-n string
True, if length of string is
non-zero.
-N file
True, if file exists and the modification time is
greater than the last access time.
-o option
True, if option named option is on.
-o ?option
True, if option named option is a valid option
name.
-O file
True, if file exists and is owned by the effective
user id of this process.
-p file
True, if file exists and is a FIFO special
file or a pipe.
-r file
True, if file exists and is readable by current
process.
-R name
True if variable name is a name reference.
-s file
True, if file exists and has size greater than
zero.
-S file
True, if file exists and is a socket.
-t fildes
True, if file descriptor number fildes is open and
associated with a terminal device.
-u file
True, if file exists and it has its setuid
bit set.
-v name
True, if variable name is a valid variable name
and is set.
-w file
True, if file exists and is writable by current
process.
-x file
True, if file exists and is executable by current
process. If file exists and is a directory, then true if the current
process has permission to search in the directory.
-z string
True, if length of string is zero.
file1 -ef file2
True, if file1 and file2 exist and refer to
the same file.
file1 -nt file2
True, if file1 exists and file2 does not,
or file1 is newer than file2.
file1 -ot file2
True, if file2 exists and file1 does not,
or file1 is older than file2.
string
True, if string is not null.
string == pattern
True, if string matches pattern. Any part
of pattern can be quoted to cause it to be matched as a string. With a
successful match to pattern, the .sh.match array variable
contains the match and sub-pattern matches.
string = pattern
Same as ==, but is obsolete.
string != pattern
True, if string does not match pattern.
When the string matches the pattern the .sh.match array
variable contains the match and sub-pattern matches.
string =~ ere
True if string matches the pattern
~(E)ere where ere is an extended regular
expression.
string1 < string2
True, if string1 comes before string2 based
on ASCII value of their characters.
string1 > string2
True, if string1 comes after string2 based
on ASCII value of their characters.
In each of the above expressions, if file is of the form
/dev/fd/n, where n is an integer, the test is applied
to the open file whose descriptor number is n.
The following obsolete arithmetic comparisons are also
supported:
exp1 -eq exp2
True, if exp1 is equal to exp2.
exp1 -ge exp2
True, if exp1 is greater than or equal to
exp2.
exp1 -gt exp2
True, if exp1 is greater than exp2.
exp1 -le exp2
True, if exp1 is less than or equal to
exp2.
exp1 -lt exp2
True, if exp1 is less than exp2.
exp1 -ne exp2
True, if exp1 is not equal to exp2.
A compound expression can be constructed from these primitives by
using any of the following, listed in decreasing order of precedence:
(expression)
True, if expression is true. Used to group
expressions.
! expression
True, if expression is false.
expression1 && expression2
True, if expression1 and expression2 are
both true.
expression1 || expression2
True, if either expression1 or expression2
is true.
Before a command is executed, its input and output can be redirected using a
special notation interpreted by the shell. The following can appear anywhere
in a simple command or can precede or follow a command and are not
passed on to the invoked command. Command substitution, parameter expansion,
and arithmetic substitution occur before word or digit is used
except as noted in this section. File name generation occurs only if the shell
is interactive and the pattern matches a single file. Field splitting is not
performed.
In each of the following redirections, if file is of the
form /dev/sctp/host/port,
/dev/tcp/host/port, or
/dev/udp/host/port, where host is a
hostname or host address, and port is a service specified by name or
an integer port number, then the redirection attempts to make a tcp,
sctp or udp connection to the corresponding socket.
No intervening space is allowed between the characters of
redirection operators.
<word
Use file word as standard input (file descriptor
0).
>word
Use file word as standard output (file descriptor
1). If the file does not exist then it is created. If the file exists, and the
noclobber option is on, this causes an error. Otherwise, it is
truncated to zero length.
>|word
Same as >, except that it overrides the
noclobber option.
>;word
Write output to a temporary file. If the command
completes successfully rename it to word, otherwise, delete the temporary
file. >;word cannot be used with the exec(2) built-in.
>>word
Use file word as standard output. If the file
exists, then output is appended to it (by first seeking to the end-of-file).
Otherwise, the file is created.
<>word
Open file word for reading and writing as standard
input.
<<[-]word
The shell input is read up to a line that is the same as
word after any quoting has been removed, or to an end-of-file. No
parameter substitution, command substitution, arithmetic substitution or file
name generation is performed on word. The resulting document, called a
here-document, becomes the standard input. If any character of
word is quoted, then no interpretation is placed upon the characters of
the document. Otherwise, parameter expansion, command substitution, and
arithmetic substitution occur, \NEWLINE is ignored, and \ must
be used to quote the characters \, $, `. If - is
appended to <<, then all leading tabs are stripped from
word and from the document. If # is appended to <<,
then leading SPACEs and TABs are stripped off the first line of the document
and up to an equivalent indentation is stripped from the remaining lines and
from word. A tab stop is assumed to occur at every 8 columns for the
purposes of determining the indentation.
<<<word
A short form of here document in which word
becomes the contents of the here-document after any parameter expansion,
command substitution, and arithmetic substitution occur.
<&digit
The standard input is duplicated from file descriptor
digit, and similarly for the standard output using
>&digit. See dup(2).
<&digit-
The file descriptor specified by digit is moved to
standard input. Similarly for the standard output using
>&digit-.
<&-
The standard input is closed. Similarly for the standard
output using >&-.
<&p
The input from the co-process is moved to standard
input.
>&p
The output to the co-process is moved to standard
output.
<#((expr))
Evaluate arithmetic expression expr and position
file descriptor 0 to the resulting value bytes from the start of the file. The
variables CUR and EOF evaluate to the current offset and
end-of-file offset respectively when evaluating expr.
>#((expr))
The same as <# except applies to file
descriptor 1.
<#pattern
Seek forward to the beginning of the next line containing
pattern.
<##pattern
The same as <#, except that the portion of the
file that is skipped is copied to standard output.
If one of the redirection operators is preceded by a digit, with
no intervening space, then the file descriptor number referred to is that
specified by the digit (instead of the default 0 or 1). If one of the
redirection operators other than >&- and the ># and
<# forms, is preceded by {varname} with no
intervening space, then a file descriptor number > 10 is selected
by the shell and stored in the variable varname. If >&-
or the any of the ># and <# forms is preceded by
{varname} the value of varname defines the file
descriptor to close or position. For example:
... 2>&1
means file descriptor 2 is to be opened for writing as a duplicate
of file descriptor 1 and
exec [n]<file
means open file for reading and store the file descriptor
number in variable n. The order in which redirections are specified
is significant. The shell evaluates each redirection in terms of the
(file_descriptor, file) association at the time of evaluation.
For example:
... 1>fname 2>&1
first associates file descriptor 1 with file fname. It then
associates file descriptor 2 with the file associated with file descriptor
1, that is, fname. If the order of redirections were reversed, file
descriptor 2 would be associated with the terminal (assuming file descriptor
1 had been) and then file descriptor 1 would be associated with file
fname. If a command is followed by & and job control is
not active, the default standard input for the command is the empty file
/dev/null. Otherwise, the environment for the execution of a command
contains the file descriptors of the invoking shell as modified by input and
output specifications.
The environment is a list of name-value pairs that is passed to an
executed program in the same way as a normal argument list. See
environ(5).
The names must be identifiers and the values are character
strings. The shell interacts with the environment in several ways. On
invocation, the shell scans the environment and creates a variable for each
name found, giving it the corresponding value and attributes and marking it
export. Executed commands inherit the environment. If the user
modifies the values of these variables or creates new ones, using the
export or typeset -x commands, they become part of the
environment. The environment seen by any executed command is thus composed
of any name-value pairs originally inherited by the shell, whose values can
be modified by the current shell, plus any additions which must be noted in
export or typeset -x commands. The environment for any
simple-command or function can be augmented by prefixing it with one or more
variable assignments. A variable assignment argument is a word of the form
identifier=value. Thus:
TERM=450 cmd args
and
(export TERM; TERM=450; cmd args)
are equivalent (as far as the execution of cmd is concerned
except for special built-in commands listed in the Built-Ins section,
those that are preceded with a dagger. If the obsolete -k option is
set, all variable assignment arguments are placed in the environment, even
if they occur after the command name.
The following example first prints a=b c and then
c:
echo a=b c
set -k
echo a=b c
This feature is intended for use with scripts written for early
versions of the shell and its use in new scripts is strongly
discouraged.
For historical reasons, there are two ways to define functions, the
name() syntax and the function name syntax. These are
described in the Commands section of this manual page.
Shell functions are read in and stored internally. Alias names are
resolved when the function is read. Functions are executed like commands
with the arguments passed as positional parameters. See the Execution
section of this manual page for details.
Functions defined by the function name syntax and
called by name execute in the same process as the caller and share all files
and present working directory with the caller. Traps caught by the caller
are reset to their default action inside the function. A trap condition that
is not caught or ignored by the function causes the function to terminate
and the condition to be passed on to the caller. A trap on EXIT set
inside a function is executed in the environment of the caller after the
function completes. Ordinarily, variables are shared between the calling
program and the function. However, the typeset special built-in
command used within a function defines local variables whose scope includes
the current function. They can be passed to functions that they call in the
variable assignment list that precedes the call or as arguments passed as
name references. Errors within functions return control to the caller.
Functions defined with the name() syntax and functions
defined with the function name syntax that are invoked with
the . special built-in are executed in the caller's environment and
share all variables and traps with the caller. Errors within these function
executions cause the script that contains them to abort.
The special built-in command return is used to return from
function calls.
Function names can be listed with the -f or +f
option of the typeset special built-in command. The text of
functions, when available, is also listed with -f. Functions can be
undefined with the -f option of the unset special built-in
command.
Ordinarily, functions are unset when the shell executes a shell
script. Functions that need to be defined across separate invocations of the
shell should be placed in a directory and the FPATH variable should
contain the name of this directory. They can also be specified in the
ENV file.
Each variable can have zero or more discipline functions associated with it. The
shell initially understands the discipline names get, set,
append, and unset but on most systems others can be added at run
time via the C programming interface extension provided by the builtin
built-in utility. If the get discipline is defined for a variable, it
is invoked whenever the specified variable is referenced. If the variable
.sh.value is assigned a value inside the discipline function, the
referenced variable is evaluated to this value instead. If the set
discipline is defined for a variable, it is invoked whenever the specified
variable is assigned a value. If the append discipline is defined for a
variable, it is invoked whenever a value is appended to the specified
variable. The variable .sh.value is specified the value of the variable
before invoking the discipline, and the variable is assigned the value of
.sh.value after the discipline completes. If .sh.value is
unset inside the discipline, then that value is unchanged. If the
unset discipline is defined for a variable, it is invoked whenever the
specified variable is unset. The variable is not unset unless it is unset
explicitly from within this discipline function.
The variable .sh.name contains the name of the variable for
which the discipline function is called, .sh.subscript is the
subscript of the variable, and .sh.value contains the value being
assigned inside the set discipline function. For the set
discipline, changing .sh.value changes the value that gets assigned.
The variable _ is a reference to the variable including the subscript
if any. For the set discipline, changing .sh.value will change the
value that gets assigned. Finally, the expansion ${
var.name}, when name is the name of a discipline, and there is
no variable of this name, is equivalent to the command substitution
${var.name;}.
Commands and functions that are executed as part of the list of a
namespace command that modify variables or create new ones, create a
new variable whose name is the name of the name space as given by
identifier preceded by two dots (..). When a variable whose name
is name is referenced, it is first searched for using
.identifier.name. Similarly, a function
defined by a command in the namespace list is created using the
name space name preceded by two dots (..).
When the list of a namespace command contains a
namespace command, the names of variables and functions that are
created consist of the variable or function name preceded by the list of
identifiers each preceded by two dots (..).
Outside of a name space, a variable or function created inside a
name space can be referenced by preceding it with the name space name.
By default, variables staring with .sh are in the sh
name space.
Typed variables provide a way to create data structure and objects. A type can
be defined either by a shared library, by the enum built-in command
described below, or by using the new -T option of the typeset
built-in command. With the -T option of typeset, the type name,
specified as an option argument to -T, is set with a compound variable
assignment that defines the type. Function definitions can appear inside the
compound variable assignment and these become discipline functions for this
type and can be invoked or redefined by each instance of the type. The
function name create is treated specially. It is invoked for each
instance of the type that is created but is not inherited and cannot be
redefined for each instance.
When a type is defined a special built-in command of that name is
added. These built-ins are declaration commands and follow the same
expansion rules as all the special built-in commands defined below that are
preceded by a dot (.). These commands can subsequently be used inside
further type definitions. The man page for these commands can be generated
by using the --man option or any of the other -- options
described with getopts. The -r, -a, -A, -h and -S
options of typeset are permitted with each of these new
built-ins.
An instance of a type is created by invoking the type name
followed by one or more instance names. Each instance of the type is
initialized with a copy of the sub-variables except for sub-variables that
are defined with the -s option. Variables defined with -S are
shared by all instances of the type. Each instance can change the value of
any sub-variable and can also define new discipline functions of the same
names as those defined by the type definition as well as any standard
discipline names. No additional sub-variables can be defined for any
instance.
When defining a type, if the value of a sub-variable is not set
and the -r attribute is specified, it causes the sub-variable to be a
required sub-variable. Whenever an instance of a type is created, all
required sub-variables must be specified. These sub-variables become
readonly in each instance.
When unset is invoked on a sub-variable within a type, and
the -r attribute has not been specified for this field, the value is
reset to the default value associative with the type. Invoking unset
on a type instance not contained within another type deletes all
sub-variables and the variable itself.
A type definition can be derived from another type definition by
defining the first sub-variable name as _ and defining its type as
the base type. Any remaining definitions will be additions and modifications
that apply to the new type. If the new type name is the same is that of the
base type, the type will be replaced and the original type will no longer be
accessible.
The typeset command with -T and no option argument
or operands will write all the type definitions to standard output in a form
that that can be read in to create all the types.
If the monitor option of the set command is turned on, an interactive
shell associates a job with each pipeline. It keeps a table of current jobs,
printed by the jobs command, and assigns them small integer numbers.
When a job is started asynchronously with &, the shell prints a
line which looks like:
[1] 1234
indicating that the job which was started asynchronously was job
number 1 and had one (top-level) process, whose process id was
1234.
If you are running a job and wish to stop it, CTRL-z sends a
STOP signal to the current job. The shell normally displays a message
that the job has been stopped, and displays another prompt. You can then
manipulate the state of this job, putting it in the background with the
bg command, or run some other commands and then eventually bring the
job back into the foreground with the foreground command fg. A CTRL-z
takes effect immediately and is like an interrupt in that pending output and
unread input are discarded when it is typed.
A job being run in the background stops if it tries to read from
the terminal. Background jobs are normally allowed to produce output, but
this can be disabled by giving the command sttytostop. If you set
this tty option, then background jobs stop when they try to produce
output like they do when they try to read input.
A job pool is a collection of jobs started with list
& associated with a name.
There are several ways to refer to jobs in the shell. A job can be
referred to by the process id of any process of the job or by one of the
following:
%number
The job with the specified number.
pool
All the jobs in the job pool named by pool.
pool.number
The job number number in the pool named by
pool.
%string
Any job whose command line begins with
string.
%?string
Any job whose command line contains string.
%%
Current job.
%+
Equivalent to %%.
%-
Previous job.
In addition, unless noted otherwise, wherever a job can be
specified, the name of a background job pool can be used to represent all
the jobs in that pool.
The shell learns immediately whenever a process changes state. It
normally informs you whenever a job becomes blocked so that no further
progress is possible, but only just before it prints a prompt. This is done
so that it does not otherwise disturb your work. The notify option of the
set command causes the shell to print these job change messages as
soon as they occur.
When the monitor option is on, each background job that
completes triggers any trap set for CHLD.
When you try to leave the shell while jobs are running or stopped,
you are warned that You have stopped(running) jobs. You can use the
jobs command to see what they are. If you immediately try to exit
again, the shell does not warn you a second time, and the stopped jobs are
terminated. When a login shell receives a HUP signal, it sends a
HUP signal to each job that has not been disowned with the
disown built-in command.
The INT and QUIT signals for an invoked command are ignored if the
command is followed by & and the monitor option is not
active. Otherwise, signals have the values inherited by the shell from its
parent. See the trap built-in command.
Each time a command is read, the substitutions are carried out. If the command
name matches one of the ones in the Special Built-in Commands section
of this manual page, it is executed within the current shell process. Next,
the command name is checked to see if it matches a user defined function. If
it does, the positional parameters are saved and then reset to the arguments
of the function call. A function is also executed in the current shell
process. When the function completes or issues a return, the positional
parameter list is restored. For functions defined with the function
name syntax, any trap set on EXIT within the function is
executed. The exit value of a function is the value of the last command
executed. If a command name is not a special built-in command or a user
defined function, but it is one of the built-in commands, it is executed in
the current shell process.
The shell variables PATH and FPATH define the search
path for the directory containing the command. Alternative directory names
are separated by a colon (:). The default path is
/bin:/usr/bin:, specifying /bin, /usr/bin, and the
current directory in that order. The current directory can be specified by
two or more adjacent colons, or by a colon at the beginning or end of the
path list. If the command name contains a slash (/), the search path
is not used. Otherwise, each directory in the list of directories defined by
PATH and FPATH is checked in order. If the directory being
searched is contained in the value of the FPATH variable and contains
a file whose name matches the command being searched, then this file is
loaded into the current shell environment as if it were the argument to the
. command except that only preset aliases are expanded, and a function of
the specified name is executed as described in this manual page.
If this directory is not in FPATH, the shell first
determines whether there is a built-in version of a command corresponding to
a given pathname and, if so, it is invoked in the current process. If no
built-in is found, the shell checks for a file named .paths in this
directory. If found and there is a line of the form:
FPATH=path
where path is an existing directory, then that directory is
searched immediately after the current directory as if it were found in the
FPATH variable. If path does not begin with /, it is
checked for relative to the directory being searched.
The .paths file is then checked for a line of the form:
PLUGIN_LIB=libname [ : libname ] ...
Each library named by libname will be searched for as if it
were an option argument to builtin -f and, if it contains a built-in
of the specified name, this is executed instead of a command by this
name.
Any built-in loaded from a library found this way will be
associated with the directory containing the .paths file so it will
only execute if not found in an earlier directory.
Finally, the directory will be checked for a file of the given
name. If the file has execute permission but is not an a.out file, it
is assumed to be a file containing shell commands. A separate shell is
spawned to read it. All non-exported variables are removed in this case. If
the shell command file doesn't have read permission, and/or if the
setuid and setgid bits are set on the file, then the shell
executes an agent whose job it is to set up the permissions and execute the
shell with the shell command file passed down as an open file.
If the .paths contains a line of the form:
name=value
in the first or second line, then the environment variable
name is modified by prepending the directory specified by
value to the directory list. If value is not an absolute
directory, then it specifies a directory relative to the directory in which
the executable was found. If the environment variable name does not
already exist it will be added to the environment list for the specified
command.
A parenthesized command is executed in a sub-shell without
removing non-exported variables.
The text of the last HISTSIZE (default 512) commands entered from a
terminal device is saved in a history file. The file $HOME/.sh_history
is used if the HISTFILE variable is not set or if the file it names is
not writable. A shell can access the commands of all interactive shells which
use the same named HISTFILE. The built-in command hist is used
to list or edit a portion of this file. The portion of the file to be edited
or listed can be selected by number or by giving the first character or
characters of the command. A single command or range of commands can be
specified. If you do not specify an editor program as an argument to
hist then the value of the variable HISTEDIT is used. If
HISTEDIT is unset, the obsolete variable FCEDIT is used. If
FCEDIT is not defined, then /bin/ed is used. The edited commands
are printed and executed again upon leaving the editor unless you quit without
writing. The -s option (and in obsolete versions, the editor name
-) is used to skip the editing phase and to re-execute the command. In
this case a substitution parameter of the form old=newcan
be used to modify the command before execution. For example, with the preset
alias r, which is aliased to 'hist -s', typing `r bad=good
c' re-executes the most recent command which starts with the letter
c, replacing the first occurrence of the string bad with the string
good.
Normally, each command line entered from a terminal device is simply typed
followed by a NEWLINE (RETURN or LINE FEED). If either the emacs,
gmacs, or vi option is active, the user can edit the command
line. To be in either of these edit modes set the corresponding option. An
editing option is automatically selected each time the VISUAL or
EDITOR variable is assigned a value ending in either of these option
names.
The editing features require that the user's terminal accept
RETURN as carriage return without line feed and that a SPACE must overwrite
the current character on the screen.
Unless the multiline option is on, the editing modes
implement a concept where the user is looking through a window at the
current line. The window width is the value of COLUMNS if it is
defined, otherwise 80. If the window width is too small to display
the prompt and leave at least 8 columns to enter input, the prompt is
truncated from the left. If the line is longer than the window width minus
two, a mark is displayed at the end of the window to notify the user. As the
cursor moves and reaches the window boundaries the window is centered about
the cursor. The mark is a > (<, *) if the line extends
on the right , left, or both sides of the window.
The search commands in each edit mode provide access to the
history file. Only strings are matched, not patterns, although a leading
^ in the string restricts the match to begin at the first character
in the line.
Each of the edit modes has an operation to list the files or
commands that match a partially entered word. When applied to the first word
on the line, or the first word after a ;, |, &, or
(, and the word does not begin with ~ or contain a /,
the list of aliases, functions, and executable commands defined by the
PATH variable that could match the partial word is displayed.
Otherwise, the list of files that match the specified word is displayed. If
the partially entered word does not contain any file expansion characters, a
* is appended before generating these lists. After displaying the
generated list, the input line is redrawn. These operations are called
command name listing and file name listing, respectively. There are
additional operations, referred to as command name completion and file name
completion, which compute the list of matching commands or files, but
instead of printing the list, replace the current word with a complete or
partial match. For file name completion, if the match is unique, a /
is appended if the file is a directory and a space is appended if the file
is not a directory. Otherwise, the longest common prefix for all the
matching files replaces the word. For command name completion, only the
portion of the file names after the last / are used to find the
longest command prefix. If only a single name matches this prefix, then the
word is replaced with the command name followed by a space. When using a
TAB for completion that does not yield a unique match, a subsequent
TAB provides a numbered list of matching alternatives. A specific selection
can be made by entering the selection number followed by a TAB.
The KEYBD trap can be used to intercept keys as they are typed and change
the characters that are actually seen by the shell. This trap is executed
after each character (or sequence of characters when the first character is
ESC) is entered while reading from a terminal.
The variable .sh.edchar contains the character or character
sequence which generated the trap. Changing the value of .sh.edchar
in the trap action causes the shell to behave as if the new value were
entered from the keyboard rather than the original value. The variable
.sh.edcol is set to the input column number of the cursor at the time
of the input. The variable .sh.edmode is set to ESC when in
vi insert mode and is null otherwise. By prepending
${.sh.editmode} to a value assigned to .sh.edchar it causes
the shell to change to control mode if it is not already in this mode.
This trap is not invoked for characters entered as arguments to
editing directives, or while reading input for a character search.
This mode is entered by enabling either the emacs or gmacs option.
The only difference between these two modes is the way they handle ^T.
To edit, the user moves the cursor to the point needing correction and then
inserts or deletes characters or words as needed. All the editing commands are
control characters or escape sequences. The notation for control characters is
caret (^) followed by the character.
For example, ^F is the notation for CTRL/F. This is entered
by depressing f while holding down the CTRL (control) key. The SHIFT
key is not depressed. (The notation ^? indicates the DEL (delete)
key.)
The notation for escape sequences is M- followed by a
character. For example, M-f (pronounced Meta f) is entered by
depressing ESC (ASCII 033) followed by f. M-F is the
notation for ESC followed by F.
All edit commands operate from any place on the line, not just at
the beginning. The RETURN or the LINE FEED key is not entered after edit
commands except when noted.
^F
Move the cursor forward (right) one character.
M-[C
Move the cursor forward (right) one character.
M-f
Move the cursor forward one word. The emacs
editor's idea of a word is a string of characters consisting of only letters,
digits and underscores.
^B
Move the cursor backward (left) one character.
M-[D
Move the cursor backward (left) one character.
M-b
Move the cursor backward one word.
^A
Move the cursor to the beginning of the line.
M-[H
Move the cursor to the beginning of the line.
^E
Move the cursor to the end of the line.
M-[Y
Move the cursor to the end of line.
^]char
Move the cursor forward to the character char on
the current line.
M-^]char
Move the cursor backwards to the character char on
the current line.
^X^X
Interchange the cursor and the mark.
erase
Delete the previous character. The user-defined erase
character is defined by the stty(1) command, and is usually ^H
or #.
lnext
Removes the next character's editing features. The
user-defined literal next character is defined by the stty(1) command,
or is ^V if not defined.
^D
Delete the current character.
M-d
Delete the current word.
M-^H
MetaBACKSPACE. Delete the previous word.
M-h
Delete the previous word.
M-^?
MetaDEL. Delete the previous word. If your interrupt
character is ^? (DEL, the default), this command does not work.
^T
Transpose the current character with the previous
character, and advance the cursor in emacs mode. Transpose two previous
characters in gmacs mode.
^C
Capitalize the current character.
M-c
Capitalize the current word.
M-l
Change the current word to lower case.
^K
Delete from the cursor to the end of the line. If
preceded by a numerical parameter whose value is less than the current cursor
position, delete from specified position up to the cursor. If preceded by a
numerical parameter whose value is greater than the current cursor position,
then delete from cursor up to specified cursor position.
^W
Kill from the cursor to the mark.
M-p
Push the region from the cursor to the mark on the
stack.
kill
Kill the entire current line. The user-defined kill
character is defined by the stty(1) command, usually a ^G or
@. If two kill characters are entered in succession, all kill
characters from then on cause a line feed. This is useful when using paper
terminals.
^Y
Restore the last item removed from line. Yank the item
back to the line.
^L
Line feed and print the current line.
M-^L
Clear the screen.
^@
Null character. Set mark.
M-space
MetaSPACE. Set the mark.
^J
New line. Execute the current line.
^M
Return. Execute the current line.
EOF
End-of-file character, normally ^D, is processed
as an end-of-file only if the current line is null.
^P
Fetch the previous command. Each time ^P is
entered the previous command back in time is accessed. Moves back one line
when it is not on the first line of a multi-line command.
M-[A
Equivalent to ^P.
M-<
Fetch the least recent (oldest) history line.
M->
Fetch the most recent (youngest) history line.
^N
Fetch the next command line. Each time ^N is
entered the next command line forward in time is accessed.
M-[B
Equivalent to ^N.
^Rstring
Reverse search history for a previous command line
containing string. If a parameter of zero is specified, the search is
forward. string is terminated by a RETURN or NEWLINE. If string is
preceded by a ^, the matched line must begin with string. If
string is omitted, then the next command line containing the most
recent string is accessed. In this case a parameter of zero reverses
the direction of the search.
^O
Operate. Execute the current line and fetch the next line
relative to current line from the history file.
M-digits
Escape. Define numeric parameter. The digits are taken as
a parameter to the next command. The commands that accept a parameter are:
^F, ^B, ERASE, ^C, ^D, ^K,
^R, ^P, ^N, ^], M-., M-,
M-^], M-_, M-=, M-b, M-c, M-d,
M-f, M-h, M-l, and M-^H.
M-letter
Soft-key. Search the alias list for an alias by the name
letter. If an alias of letter is defined, insert its value on
the input queue. letter must not be one of the metafunctions in this
section.
M-[letter
Soft key. Search the alias list for an alias by the name
letter. If an alias of this name is defined, insert its value on the
input queue. This can be used to program function keys on many
terminals.
M-.
The last word of the previous command is inserted on the
line. If preceded by a numeric parameter, the value of this parameter
determines which word to insert rather than the last word.
M-_
Same as M-..
M-*
Attempt filename generation on the current word. As
asterisk is appended if the word does not match any file or contain any
special pattern characters.
M-ESC
Command or file name completion as described in this
manual page.
^ITAB
Attempts command or file name completion as described in
this manual page. If a partial completion occurs, repeating this behaves as if
M-= were entered. If no match is found or entered after SPACE, a TAB is
inserted.
M-=
If not preceded by a numeric parameter, generates the
list of matching commands or file names as described in this manual page.
Otherwise, the word under the cursor is replaced by the item corresponding to
the value of the numeric parameter from the most recently generated command or
file list. If the cursor is not on a word, the word is inserted instead.
^U
Multiply parameter of next command by 4.
\
Escape the next character. Editing characters, the user's
erase, kill and interrupt (normally ^?) characters can be entered in a
command line or in a search string if preceded by a \. The \
removes the next character's editing features, if any.
M-^V
Display the version of the shell.
M-#
If the line does not begin with a #, a # is
inserted at the beginning of the line and after each NEWLINE, and the line is
entered. This causes a comment to be inserted in the history file. If the line
begins with a #, the # is deleted and one # after each
NEWLINE is also deleted.
There are two typing modes. Initially, when you enter a command you are in the
input mode. To edit, the user enters control mode by typing ESC (033) and
moves the cursor to the point needing correction and then inserts or deletes
characters or words as needed. Most control commands accept an optional repeat
count prior to the command.
When in vi mode on most systems, canonical processing is initially
enabled and the command is echoed again if the speed is 1200 baud or greater
and it contains any control characters or less than one second has elapsed
since the prompt was printed. The ESC character terminates canonical
processing for the remainder of the command and the user can then modify the
command line. This scheme has the advantages of canonical processing with
the type-ahead echoing of raw mode.
If the option viraw is also set, the terminal is always
have canonical processing disabled. This mode is implicit for systems that
do not support two alternate end of line delimiters, and might be helpful
for certain terminals.
By default the editor is in input mode.
The following input edit commands are supported:
ERASE
User defined erase character as defined by the
stty command, usually ^H or #. Delete previous
character.
^W
Delete the previous blank separated word. On some systems
the viraw option might be required for this to work.
EOF
As the first character of the line causes the shell to
terminate unless the ignoreeof option is set. Otherwise this character
is ignored.
lnext
User defined literal next character as defined by the
stty(1) or ^V if not defined. Removes the next character's
editing features, if any. On some systems the viraw option might be
required for this to work.
\
Escape the next ERASE or KILL character.
^I TAB
Attempts command or file name completion as described in
this manual page and returns to input mode. If a partial completion occurs,
repeating this behaves as if = were entered from control mode. If no
match is found or entered after SPACE, a TAB is inserted.
The motion edit commands move the cursor.
The following motion edit commands are supported:
[count]l
Move the cursor forward (right) one character.
[count][C
Move the cursor forward (right) one character.
[count]w
Move the cursor forward one alphanumeric word.
[count]W
Move the cursor to the beginning of the next word that
follows a blank.
[count]e
Move the cursor to the end of the word.
[count]E
Move the cursor to the end of the current blank delimited
word.
[count]h
Move the cursor backward (left) one character.
[count][D
Move the cursor backward (left) one character.
[count]b
Move the cursor backward one word.
[count]B
Move the cursor to the preceding blank separated
word.
[count]|
Move the cursor to column count.
[count]fc
Find the next character c in the current
line.
[count]Fc
Find the previous character c in the current
line.
[count]tC
Equivalent to f followed by h.
[count]Tc
Equivalent to F followed by l.
[count];
Repeat count times the last single character find
command: f, F, t, or T.
[count],
Reverse the last single character find command
count times.
0
Move the cursor to the start of line.
^
Move the cursor to start of line.
[H
Move the cursor to the first non-blank character in the
line.
$
Move the cursor to the end of the line.
[Y
Move the cursor to the end of the line.
%
Moves to balancing (, ), {,
}, [, or ]. If cursor is not on one of the characters
described in this section, the remainder of the line is searched for the first
occurrence of one of the characters first.
The search edit commands access your command history.
The following search edit commands are supported:
[count]k
Fetch the previous command. Each time k is
entered, the previous command back in time is accessed.
[count]-
Fetch the previous command. Each time
k is
entered, the previous command back in time is accessed.
Equivalent to k.
[count][A
Fetch the previous command. Each time
k is
entered, the previous command back in time is accessed.
Equivalent to k.
[count]j
Fetch the next command. Each time j is entered,
the next command forward in time is accessed.
[count]+
Fetch the next command. Each time
j is entered,
the next command forward in time is accessed.
Equivalent to j.
[count][B
Fetch the next command. Each time
j is entered,
the next command forward in time is accessed.
Equivalent to j.
[count]G
Fetch command number count. The default is the
least recent history command.
/string
Search backward through history for a previous command
containing string. string is terminated by a RETURN or NEWLINE.
If string is preceded by a ^, the matched line must begin with
string. If string is null, the previous string is used.
?string
Search forward through history for a previous command
containing
string.
string is terminated by a RETURN or NEWLINE.
If string is preceded by a
^, the matched line must begin with
string. If
string is null, the previous string is used.
Same as / except that search is in the forward
direction.
n
Search in the backwards direction for the next match of
the last pattern to / or ? commands.
N
Search in the forward direction for next match of the
last pattern to / or ?.
The following commands modify the line:
a
Enter input mode and enter text after the current
character.
A
Append text to the end of the line. Equivalent to
$a.
[count]cmotion
c[count]motion
Delete current character through the character that
motion would move the cursor to and enter input mode. If motion
is c, the entire line is deleted and input mode entered.
C
Delete the current character through the end of line and
enter input mode. Equivalent to c$.
S
Equivalent to cc.
[count]s
Replace characters under the cursor in input mode.
D[count]dmotion
Delete the current character through the end of line.
Equivalent to d$.
d[count]motion
Delete current character through the character that
motion would move to. If motion is d , the entire line is
deleted.
i
Enter input mode and insert text before the current
character.
I
Insert text before the beginning of the line. Equivalent
to 0i.
[count]P
Place the previous text modification before the
cursor.
[count]p
Place the previous text modification after the
cursor.
R
Enter input mode and replace characters on the screen
with characters you type overlay fashion.
[count]rc
Replace the count characters starting at the
current cursor position with c, and advance the cursor.
[count]x
Delete current character.
[count]X
Delete preceding character.
[count].
Repeat the previous text modification command.
[count]~
Invert the case of the count characters starting
at the current cursor position and advance the cursor.
[count]_
Causes the count word of the previous command to
be appended and input mode entered. The last word is used if count is
omitted.
*
Causes an * to be appended to the current word and
file name generation attempted. If no match is found, it rings the bell.
Otherwise, the word is replaced by the matching pattern and input mode is
entered.
\
Command or file name completion as described in this
manual page.
The following miscellaneous edit commands are supported:
[count]ymotion
y[count]motion
Yank the current character through the character to which
motion would move the cursor. Put the yanked characters in the delete
buffer. The text and cursor position are unchanged.
yy
Yank the current line.
Y
Yank the current line from the current cursor location to
the end of the line. Equivalent to y$.
u
Undo the last text modifying command.
U
Undo all the text modifying commands performed on current
line.
[count]V
Return the command :
hist -e ${VISUAL:-${EDITOR:-vi}} count
in the input buffer. If count is omitted, the current line
is used.
^L
Line feed and print the current line. This command only
works in control mode.
^J
New line. Execute the current line, regardless of
mode.
^M
Return. Execute the current line, regardless of
mode.
#
If the first character of the command is a
# ,
delete this
# and each
# that follows a NEWLINE.
Otherwise, send the line after inserting a # in front of
each line in the command.
This is command is useful for causing the current line to be
inserted in the history as a comment and un-commenting previously commented
commands in the history file.
[count]=
If
count is not specified, generate the list of
matching commands or file names as described in this manual page.
Otherwise, replace the word at the current cursor location with
the count item from the most recently generated command or file list.
If the cursor is not on a word, it is inserted after the current cursor
location.
@letter
Search your alias list for an alias by the name
letter. If an alias of this name is defined, insert its value on the
input queue for processing.
^V
Display version of the shell.
The following simple-commands are executed in the shell process. Input and
output redirection is permitted. Unless otherwise indicated, the output is
written on file descriptor 1 and the exit status, when there is no
syntax error, is 0. Except for :, true, false,
echo, newgrp, and login, all built-in commands accept
-- to indicate the end of options. They also interpret the option
--man as a request to display the manual page onto standard error and
-? as a help request which prints a usage message on standard error.
Commands that are preceded by one or two ++ symbols are
special built-in commands and are treated specially in the following
ways:
- 1.
- Variable assignment lists preceding the command remain in effect when the
command completes.
- 2.
- I/O redirections are processed after variable assignments.
- 3.
- Errors cause a script that contains them to abort.
- 4.
- They are not valid function names.
- 5.
- Words following a command preceded by ++ that are in the format of
a variable assignment are expanded with the same rules as a variable
assignment. This means that tilde substitution is performed after the
= sign and field splitting and file name generation are not
performed.
+ : [arg ...]
The command only expands parameters.
+ . name [arg ...]
If name is a function defined with the
function name reserved word syntax, the function is executed in
the current environment (as if it had been defined with the name()
syntax.) Otherwise if name refers to a file, the file is read in its
entirety and the commands are executed in the current shell environment. The
search path specified by PATH is used to find the directory containing the
file. If any arguments arg are specified, they become the positional
parameters while processing the . command and the original positional
parameters are restored upon completion. Otherwise the positional parameters
are unchanged. The exit status is the exit status of the last command
executed.
++ alias [-ptx] [name[
=value]] ...
alias with no arguments prints the list of aliases
in the form name=value on standard output. The -p
option causes the word alias to be inserted before each one. When one or more
arguments are specified, an alias is defined for each name whose
value is specified. A trailing space in value causes the next
word to be checked for alias substitution. The obsolete -t option is
used to set and list tracked aliases. The value of a tracked alias is the full
pathname corresponding to the specified name. The value becomes
undefined when the value of PATH is reset but the alias remains
tracked. Without the -t option, for each name in the argument
list for which no value is specified, the name and value of the alias
is printed. The obsolete -x option has no effect. The exit status is
non-zero if a name is specified, but no value, and no alias has
been defined for the name.
bg [ job...]
This command is only on systems that support job control.
Puts each specified job into the background. The current job is put in
the background if job is not specified. See the Jobs section of
this manual page for a description of the format of job.
+ break [n]
Exit from the enclosing for, while,
until, or select loop, if any. If n is specified, then
break n levels.
builtin [-ds ] [-f file]
[name ...]
If
name is not specified, and no
-f option
is specified, the built-ins are printed on standard output. The
-s
option prints only the special built-ins. Otherwise, each
name
represents the pathname whose basename is the name of the built-in. The entry
point function name is determined by prepending
b_ to the built-in
name. A built-in specified by a pathname will only be executed when that
pathname would be found during the path search. Built-ins found in libraries
loaded via the
.paths file will be associate with the pathname of the
directory containing the
.paths file.
The ISO C/C++ prototype is bmycommand(int argc, char
*argv[], void *context) for the built-in command mycommand where
argv is an array of argc elements and context is an
optional pointer to a Shell_t structure as described in
<ast/shell.h> Special built-ins cannot be bound to a pathname
or deleted. The -d option deletes each of the specified built-ins. On
systems that support dynamic loading, the -f option names a shared
library containing the code for built-ins. The shared library prefix and/or
suffix, which depend on the system, can be omitted. Once a library is
loaded, its symbols become available for subsequent invocations of
builtin. Multiple libraries can be specified with separate
invocations of the builtin command. Libraries are searched in the
reverse order in which they are specified. When a library is loaded, it
looks for a function in the library whose name is lib_init() and
invokes this function with an argument of 0.
cd [-LP] [arg]
cd [-LP] old new
This command has two forms.
In the first form it changes the current directory to arg.
If arg is a -, the directory is changed to the previous
directory. The shell variable HOME is the default arg. The
variable PWD is set to the current directory. The shell variable
CDPATH defines the search path for the directory containing
arg. Alternative directory names are separated by a colon (:).
The default path is NULL (specifying the current directory). The
current directory is specified by a null path name, which can appear
immediately after the equal sign or between the colon delimiters anywhere
else in the path list. If arg begins with a /, the search path
is not used. Otherwise, each directory in the path is searched for
arg.
The second form of cd substitutes the string new for
the string old in the current directory name, PWD, and tries
to change to this new directory. By default, symbolic link names are treated
literally when finding the directory name. This is equivalent to the
-L option. The -P option causes symbolic links to be resolved
when determining the directory. The last instance of -L or -P
on the command line determines which method is used. The cd command
cannot be executed by rksh93.
command [-pvVx] name
[arg ...]
Without the
-v or
-V options, executes
name with the arguments specified by
arg.
The -p option causes a default path to be searched rather
than the one defined by the value of PATH. Functions are not searched
when finding name. In addition, if name refers to a special
built-in, none of the special properties associated with the leading daggers
are honored. For example, the predefined alias redirect='command
exec' prevents a script from terminating when an invalid redirection is
specified.
With the -x option, if command execution would result in a
failure because there are too many arguments, errno E2BIG, the shell
invokes command name multiple times with a subset of the arguments on
each invocation. Arguments that occur prior to the first word that expands
to multiple arguments and after the last word that expands to multiple
arguments are passed on each invocation. The exit status is the maximum
invocation exit status.
With the -v option, command is equivalent to the
built-in whence command described in this section. The -V
option causes command to act like whence -v.
+continue [n]
Resumes the next iteration of the enclosing for,
while, until, or select loop. If n is specified,
then resume at the nth enclosing loop.
disown [job...]
Causes the shell not to send a HUP signal to each
specified job, or all active jobs if job is omitted, when a
login shell terminates.
echo [arg ...]
When the first arg does not begin with a -,
and none of the arguments contain a backslash (\), prints each of its
arguments separated by a SPACE and terminated by a NEWLINE. Otherwise, the
behavior of echo is system dependent and print or printf
described in this section should be used. See echo(1) for usage and
description.
++enum [ -i ] type[=(value ...)
]
Creates a declaration command named type that is an
integer type that allows one of the specified values as enumeration names. If
=(value ...) is omitted, then type must be an indexed array variable
with at least two elements and the values are taken from this array variable.
If -i is specified the values are case insensitive.
+eval [arg ...]
The arguments are read as input to the shell and the
resulting commands are executed.
+exec [-c] [-a name ...]
[arg ...]
If arg is specified, the command specified by the
arguments is executed in place of this shell without creating a new process.
The -c option causes the environment to be cleared before applying
variable assignments associated with the exec invocation. The -a option
causes name rather than the first arg, to become argv[0]
for the new process. Input and output arguments can appear and affect the
current process. If arg is not specified, the effect of this command is
to modify file descriptors as prescribed by the input/output redirection list.
In this case, any file descriptor numbers greater than 2 that are
opened with this mechanism are closed when invoking another program.
+exit [n]
Causes the shell to exit with the exit status specified
by n. The value is the least significant 8 bits of the specified
status. If n is omitted, then the exit status is that of the last
command executed. An end-of-file also causes the shell to exit except for a
shell which has the ignoreeof option turned on. See set.
++export [-p]
[name[=value]] ...
If name is not specified, the names and values of
each variable with the export attribute are printed with the values quoted in
a manner that allows them to be re-entered. The export command is the
same as typeset -x except that if you use export within a
function, no local variable is created. The -p option causes the word
export to be inserted before each one. Otherwise, the specified names
are marked for automatic export to the environment of subsequently-executed
commands.
false
Does nothing, and exits 1. Used with until
for infinite loops.
fg [job ...]
This command is only on systems that support job control.
Each job specified is brought to the foreground and waited for in the
specified order. Otherwise, the current job is brought into the foreground.
See Jobs for a description of the format of job.
getconf [name
[pathname]]
Prints the current value of the configuration parameter
specified by
name. The configuration parameters are defined by the IEEE
POSIX 1003.1 and IEEE POSIX 1003.2 standards. See
pathconf(2) and
sysconf(3C).
The pathname argument is required for parameters whose
value depends on the location in the file system. If no arguments are
specified, getconf prints the names and values of the current
configuration parameters. The pathname / is used for each of the
parameters that requires pathname.
getopts [ -a name]
optstring vname [arg ...]
Checks arg for legal options. If arg is
omitted, the positional parameters are used. An option argument begins with a
+ or a -. An option that does not begin with + or
- or the argument -- ends the options. Options beginning with
+ are only recognized when optstring begins with a +.
optstring contains the letters that getopts recognizes. If a
letter is followed by a :, that option is expected to have an argument.
The options can be separated from the argument by blanks. The option
-?causes getopts to generate a usage message on standard error.
The -a option can be used to specify the name to use for the usage
message, which defaults to $0. getopts places the next option letter it
finds inside variable vname each time it is invoked. The option letter
is prepended with a + when arg begins with a +. The index
of the next arg is stored in OPTIND. The option argument, if
any, gets stored in OPTARG. A leading : in optstring causes
getopts to store the letter of an invalid option in OPTARG, and
to set vname to ? for an unknown option and to: when a required
option argument is missing. Otherwise, getopts prints an error message.
The exit status is non-zero when there are no more options. There is no
way to specify any of the options :, +, -, ?,
[, and ]. The option # can only be specified as the first
option.
hist [ -e
ename][-nlr] [
first[last ] ]
hist -s [ old=new ] [
command]
In the first form, a range of commands from first
to last is selected from the last HISTSIZE commands that were
typed at the terminal. The arguments first and last can be
specified as a number or as a string. A string is used to locate the most
recent command starting with the specified string. A negative number is used
as an offset to the current command number. If the -l option is selected, the
commands are listed on standard output. Otherwise, the editor program
ename is invoked on a file containing these keyboard commands. If
ename is not supplied, then the value of the variable HISTEDIT
is used. If HISTEDIT is not set, then FCEDIT (default
/bin/ed) is used as the editor. When editing is complete, the edited
command(s) is executed if the changes have been saved. If last is not
specified, then it is set to first. If first is not specified,
the default is the previous command for editing and -16 for listing.
The option -r reverses the order of the commands and the option
-n suppresses command numbers when listing. In the second form,
command is interpreted as first described in this section and
defaults to the last command executed. The resulting command is executed after
the optional substitution old=new is performed.
jobs -lnp [job ...]
Lists information about each specified job, or all active
jobs if job is omitted. The -l option lists process ids in
addition to the normal information. The -n option only displays jobs
that have stopped or exited since last notified. The -p option causes
only the process group to be listed. See Jobs for a description of the
format of job.
kill [-s signame] job
...
kill [-n signum] job ...
kill -Ll [sig ...]
Sends either the TERM (terminate) signal or the
specified signal to the specified jobs or processes. Signals are either
specified by number with the -n option or by name with the -s
option (as specified in <signal.h>, stripped of the prefix
`SIG with the exception that SIGCLD is named CHLD). For
backward compatibility, the n and s can be omitted and the
number or name placed immediately after the -. If the signal being sent
is TERM (terminate) or HUP (hang up), then the job or process is
sent a CONT (continue) signal if it is stopped. The argument job
can be the process id of a process that is not a member of one of the active
jobs. See Jobs for a description of the format of job. In the
third form, kill -l or kill -L, if sig is not specified,
the signal names are listed. The -l option lists only the signal names
whereas -L lists each signal name and corresponding number. Otherwise,
for each sig that is a name, the corresponding signal number is listed.
For each sig that is a number, the signal name corresponding to the
least significant 8 bits of sig is listed.
let [arg ...]
Each arg is a separate arithmetic expression to be
evaluated. let only recognizes octal constants starting with 0
when the set option letoctal is on. See the Arithmetic
Evaluation section of this manual page for a description of arithmetic
expression evaluation. The exit status is 0 if the value of the last
expression is non-zero, and 1 otherwise.
+newgrp [arg ...]
Equivalent to exec /bin/newgrp arg
...
print [-CRenprsv] [ -u unit]
[ -f format ] [ arg ...]
With no options or with option
- or
--,
each
arg is printed on standard output. The
-f option causes the
arguments to be printed as described by
printf. In this case, any
e,
n,
r, or
R options are ignored. Otherwise,
unless the
-R or
-r, are specified, the following escape
conventions are applied:
\a
Alert character (ASCII 07)
\b
Backspace character (ASCII 010)
\c
Causes print to end without processing more arguments and
not adding a NEWLINE
\f
Form-feed character (ASCII 014)
\n
NEWLINE character (ASCII 012)
\r
RETURN character (ASCII 015)
\t
TAB character (ASCII 011)
\v
Vertical TAB character (ASCII 013)
\E
Escape character (ASCII 033)
\\
Backslash character \
\0x
Character defined by the 1, 2, or 3-digit octal string
specified by x
The -R option prints all subsequent arguments and options
other than -n. The -e causes the escape conventions to be
applied This is the default behavior. It reverses the effect of an earlier
-r. The -p option causes the arguments to be written onto the
pipe of the process spawned with |& instead of standard output.
The -v option treats each arg as a variable name and writes
the value in the printf %B format. The -C option treats each
arg as a variable name and writes the values in the printf %#B
format. The -s option causes the arguments to be written onto the
history file instead of standard output. The -u option can be used to
specify a one digit file descriptor unit number unit on which the
output is placed. The default is 1. If the option -n is used,
no NEWLINE is added to the output.
printf format [arg ...]
The arguments
arg are printed on standard output
in accordance with the
ANSI-C formatting rules associated with the
format string
format. If the number of arguments exceeds the number of
format specifications, the format string is reused to format remaining
arguments. The following extensions can also be used:
%b
A %b format can be used instead of %s to
cause escape sequences in the corresponding arg to be expanded as
described in print.
%B
A %B option causes each of the arguments to be
treated as variable names and the binary value of the variables is printed.
This is most useful for variables with an attribute of b.
%H
A %H format can be used instead of %s to
cause characters in arg that are special in HTML and XML
to be output as their entity name. The alternate flag # formats the
output for use as a URI.
%P
A %P format can be used instead of %s to
cause arg to be interpreted as an extended regular expression and be
printed as a shell pattern.
%R
A %R format can be used instead of %s to
cause arg to be interpreted as a shell pattern and to be printed as an
extended regular expression.
%q
A %q format can be used instead of %s to
cause the resulting string to be quoted in a manner than can be input again to
the shell. When q is preceded by the alternative format specifier,
#, the string is quoted in manner suitable as a field in a .csv
format file.
%(date-format)
A %(date-format)T format can be use
to treat an argument as a date/time string and to format the date/time
according to the date-format as defined for the date(1)
command.
%Z
A %Z format outputs a byte whose value is 0.
%d
The precision field of the %d format can be followed by a
. and the output base. In this case, the # flag character causes
base# to be prepended.
#
The
# flag, when used with the
%d format
without an output base, displays the output in powers of 1000 indicated by one
of the following suffixes:
k M G T P E, and when used with the
%i format displays the output in powers of 1024 indicated by one of the
following suffixes:
Ki Mi Gi Ti Pi Ei.
=
The = flag centers the output within the specified
field width.
L
The L flag, when used with the %c or
%s formats, treats precision as character width instead of byte
count.
,
The , flag, when used with the %d or
%f formats, separates groups of digits with the grouping delimiter (,
in groups of 3 in the C locale).
pwd [-LP]
Outputs the value of the current working directory. The
-L option is the default. It prints the logical name of the current
directory. If the -P option is specified, all symbolic links are
resolved from the name. The last instance of -L or -P on the
command line determines which method is used.
read [-ACSprsv] [-d
delim] [ -n n] [[ -N n]
[[-t timeout] [-u unit]
[vname?prompt] [ vname ...
]
The shell input mechanism. One line is read and is broken
up into fields using the characters in IFS as separators. The escape
character, \, is used to remove any special meaning for the next
character and for line continuation. The -d option causes the read to
continue to the first character of delim rather than NEWLINE.
The -n option causes at most n bytes to read rather a full line
but returns when reading from a slow device as soon as any characters have
been read. The -N option causes exactly n to be read unless an
end-of-file has been encountered or the read times out because of the
-t option. In raw mode, -r, the \ character is not
treated specially. The first field is assigned to the first vname, the
second field to the second vname, etc., with leftover fields assigned
to the last vname. When vname has the binary attribute and
-n or -N is specified, the bytes that are read are stored
directly into the variable. If the -v is specified, then the value of the
first vname is used as a default value when reading from a terminal
device. The -A option causes the variable vname to be unset and
each field that is read to be stored in successive elements of the indexed
array vname. The -C option causes the variable vname to be read
as a compound variable. Blanks will be ignored when finding the beginning open
parenthesis. The -S option causes the line to be treated like a record
in a .csv format file so that double quotes can be used to allow the delimiter
character and the new-line character to appear within a field. The -p
option causes the input line to be taken from the input pipe of a process
spawned by the shell using |&. If the -s option is present,
the input is saved as a command in the history file. The option -u can
be used to specify a one digit file descriptor unit unit to read from.
The file descriptor can be opened with the exec special built-in
command. The default value of unit n is 0. The option -t
is used to specify a time out in seconds when reading from a terminal or pipe.
If vname is omitted, then REPLY is used as the default vname. An
end-of-file with the -p option causes cleanup for this process so that
another can be spawned. If the first argument contains a ?, the
remainder of this word is used as a prompt on standard error when the shell is
interactive. The exit status is 0 unless an end-of-file is encountered
or read has timed out.
++readonly [-p] [
vname[=value]] ...
If vname is not specified, the names and values of
each variable with the read-only attribute is printed with the values quoted
in a manner that allows them to be input again. The -p option causes
the word readonly to be inserted before each one. Otherwise, the
specified vnames are marked readonly and these names cannot be
changed by subsequent assignment.
+return [n]
Causes a shell function or script to return to the
invoking script with the exit status specified by n. The value is the
least significant 8 bits of the specified status. If n is omitted, then
the return status is that of the last command executed. If return is invoked
while not in a function or a script, then it behaves the same as exit.
+set [ ±BCGabefhkmnoprstuvx] [±o [
option ] ] ... [ ±A vname]
[arg...]
The
set command supports the following options:
-a
All subsequent variables that are defined are
automatically exported.
-A
Array assignment. Unset the variable vname and
assign values sequentially from the arg list. If +A is used, the
variable vname is not unset first.
-b
Prints job completion messages as soon as a background
job changes state rather than waiting for the next prompt.
-B
Enable brace pattern field generation. This is the
default behavior.
-C
Prevents redirection (>) from truncating
existing files. Files that are created are opened with the O_EXCL mode.
Requires >| to truncate a file when turned on.
-e
Unless contained in a || or &&
command, or the command following an if, while or until
command or in the pipeline following !, if a command has a non-zero
exit status, execute the ERR trap, if set, and exit. This mode is
disabled while reading profiles.
-f
Disables file name generation.
-G
Causes the pattern ** by itself to match files and
zero or more directories and subdirectories when used for file name
generation. If followed by a / only directories and subdirectories are
matched.
-h
Each command becomes a tracked alias when first
encountered.
-k
Obsolete. All variable assignment arguments are placed in
the environment for a command, not just those that precede the command
name.
-m
Background jobs run in a separate process group and a
line prints upon completion. The exit status of background jobs is reported in
a completion message. On systems with job control, this option is turned on
automatically for interactive shells.
-n
Read commands and check them for syntax errors, but do
not execute them. Ignored for interactive shells.
-o
If no option name is supplied, the list of options and
their current settings are written to standard output. When invoked with a
+, the options are written in a format that can be input again to the
shell to restore the settings. This option can be repeated to enable or
disable multiple options.
The following argument can be one of the following option
names:
allexport
Same as -a.
bgnice
All background jobs are run at a lower priority. This is
the default mode.
braceexpand
Same as -B.
emacs
Puts you in an emacs style inline editor for
command entry.
errexit
Same as -e.
globstar
Same as -G.
gmacs
Puts you in a gmacs style inline editor for
command entry.
ignoreeof
The shell does not exit on end-of-file. The command
exit must be used.
keyword
Same as -k.
letoctal
The let command allows octal constants starting
with 0.
markdirs
All directory names resulting from file name generation
have a trailing / appended.
monitor
Same as -m.
multiline
The built-in editors use multiple lines on the screen for
lines that are longer than the width of the screen. This might not work for
all terminals.
noclobber
Same as -C.
noexec
Same as -n.
noglob
Same as -f.
nolog
Do not save function definitions in the history
file.
notify
Same as -b.
nounset
Same as -u.
pipefail
A pipeline does not complete until all components of the
pipeline have completed, and the return value is the value of the last
non-zero command to fail or zero if no command has failed.
privileged
Same as -p.
showme
When enabled, simple commands or pipelines preceded by a
a semicolon (;) is displayed as if the xtrace option were
enabled but is not executed. Otherwise, the leading ; is ignored.
trackall
Same as -h.
verbose
Same as -v.
vi
Puts you in insert mode of a vi style inline
editor until you hit the escape character 033. This puts you in control mode.
A return sends the line.
viraw
Each character is processed as it is typed in vi
mode.
xtrace
Same as
-x.
If no option name is supplied, the current options settings are
printed.
-p
Disables processing of the $HOME/.profile file and
uses the file /etc/suid_profile instead of the ENV file. This
mode is on whenever the effective uid (gid) is not equal to the
real uid (gid). Turning this off causes the effective uid
and gid to be set to the real uid and gid.
-r
Enables the restricted shell. This option cannot be unset
once set.
-s
Sort the positional parameters lexicographically.
-t
Obsolete. Exit after reading and executing one
command.
-u
Treat unset parameters as an error when
substituting.
-v
Print shell input lines as they are read.
-x
Print commands and their arguments as they are
executed.
--
Do not change any of the options. This is useful in
setting $1 to a value beginning with -. If no arguments follow
this option then the positional parameters are unset.
As an obsolete feature, if the first arg is - then the
-x and -v options are turned off and the next arg is
treated as the first argument. Using + rather than - causes
these options to be turned off. These options can also be used upon
invocation of the shell. The current set of options can be found in
$-. Unless -A is specified, the remaining arguments are
positional parameters and are assigned, in order, to $1 $2 .... If no
arguments are specified, then the names and values of all variables are
printed on the standard output.
+shift [n]
The positional parameters from $n+1
... are renamed $1 ..., the default n is 1. The
parameter n can be any arithmetic expression that evaluates to a
non-negative number less than or equal to $#.
sleep seconds
Suspends execution for the number of decimal seconds or
fractions of a second specified by seconds.
+trap -p [action]
[sig] ...
The -p option causes the trap action associated
with each trap as specified by the arguments to be printed with appropriate
quoting. Otherwise, action is processed as if it were an argument to
eval when the shell receives signal(s) sig. Each sig can
be specified as a number or as the name of the signal. Trap commands are
executed in order of signal number. Any attempt to set a trap on a signal that
was ignored on entry to the current shell is ineffective. If action is
omitted and the first sig is a number, or if action is -,
then the trap(s) for each sig are reset to their original values. If
action is the null string then this signal is ignored by the shell and
by the commands it invokes. If sig is ERR then action is
executed whenever a command has a non-zero exit status. If sig
is DEBUG then action is executed before each command. The
variable .sh.command contains the contents of the current command line
when action is running. If sig is 0 or EXIT and
the trap statement is executed inside the body of a function defined with the
function name syntax, then the command action is executed
after the function completes. If sig is 0 or EXIT for a
trap set outside any function then the command action is executed on
exit from the shell. If sig is KEYBD, then action is
executed whenever a key is read while in emacs, gmacs, or
vi mode. The trap command with no arguments prints a list of
commands associated with each signal number.
true
Does nothing, and exits 0. Used with while for
infinite loops.
++typeset [±ACHSfblmnprtux ] [
±EFLRXZi[n] ] [ ±M [
mapname ] ] [ -T [
tname=(assign_list) ] ] [ -h
str ] [ -a [type] ] [
vname[=value ] ]
Sets attributes and values for shell variables and
functions. When invoked inside a function defined with the
function
name syntax, a new instance of the variable
vname is created,
and the variable's value and type are restored when the function completes.
Using + rather than - causes these options to be
turned off. If no vname arguments are specified, a list of
vnames (and optionally the values) of the variables is
printed. Using + rather than - keeps the values from being
printed.) The -p option causes typeset followed by the option
letters to be printed before each name rather than the names of the options.
If any option other than -p is specified, only those variables which
have all of the specified options are printed. Otherwise, the vnames
and attributes of all variables that have attributes are printed.
The following list of attributes can be specified:
-a
Declares vname to be an indexed array. This is
optional unless except for compound variable assignments.
-A
Declares vname to be an associative array.
Sub-scripts are strings rather than arithmetic expressions.
-b
The variable can hold any number of bytes of data. The
data can be text or binary. The value is represented by the base64
encoding of the data. If -Z is also specified, the size in bytes of the
data in the buffer is determined by the size associated with the -Z. If
the base64 string assigned results in more data, it is truncated.
Otherwise, it is filled with bytes whose value is zero. The printf
format %B can be used to output the actual data in this buffer instead
of the base64 encoding of the data.
-C
Causes each vname to be a compound variable. If
value names a compound variable it is copied into vname.
Otherwise, it unsets each vname.
-E
Declares vname to be a double precision floating
point number. If n is non-zero, it defines the number of
significant figures that are used when expanding vname. Otherwise, ten
significant figures is used.
-f
The names refer to function names rather than variable
names. No assignments can be made and the only other valid options are
-t,
-u, and
-x. The
-t option turns on execution
tracing for this function. The
-u option causes this function to be
marked undefined. The
FPATH variable is searched to find the function
definition when the function is referenced. If no options other than
-f
is specified, then the function definition is displayed on standard output. If
+f is specified, then a line containing the function name followed by a
shell comment containing the line number and path name of the file where this
function was defined, if any, is displayed. The names refer to function names
rather than variable names. No assignments can be made and the only other
valid options are
-S, -t, -u and
-x. The
-S can be used
with discipline functions defined in a type to indicate that the function is
static. For a static function, the same method will be used by all instances
of that type no matter which instance references it. In addition, it can only
use value of variables from the original type definition. These discipline
functions cannot be redefined in any type instance. The
-t option turns
on execution tracing for this function. The
-u option causes this
function to be marked undefined. The
FPATH variable will be searched to
find the function definition when the function is referenced. If no options
other than
-f is specified, then the function definition will be
displayed on standard output. If
+f is specified, then a line
containing the function name followed by a shell comment containing the line
number and path name of the file where this function was defined, if any, is
displayed. The exit status can be used to determine whether the function is
defined so that
typeset -f .sh.math. name will return 0 when
math function
name is defined and non-zero otherwise.
The -i attribute cannot be specified with -f.
-F
Declares vname to be a double precision floating
point number. If n is non-zero, it defines the number of places
after the decimal point that are used when expanding vname. Otherwise
ten places after the decimal point is used.
-h
Used within type definitions to add information when
generating information about the sub-variable on the man page. It is ignored
when used outside of a type definition. When used with -f the
information is associated with the corresponding discipline function.
-H
This option provides UNIX to hostname file mapping on
non-UNIX machines.
-i
Declares
vname to be represented internally as
integer. The right hand side of an assignment is evaluated as an arithmetic
expression when assigning to an integer. If
n is
non-zero, it
defines the output arithmetic base, otherwise the output base is ten.
The -i attribute cannot be specified along with -R,
-L, -Z, or -f.
-l
Used with -i, -E or -F to indicate long
integer, or long float. Otherwise, all upper-case characters are converted to
lower-case. The upper-case option, -u, is turned off. Equivalent to
-M tolower.
-L
Left justify and remove leading blanks from
value.
If
n is
non-zero, it defines the width of the field, otherwise
it is determined by the width of the value of first assignment. When the
variable is assigned to, it is filled on the right with blanks or truncated,
if necessary, to fit into the field. The
-R option is turned off.
The -i attribute cannot be specified with -L.
-m
moves or renames the variable. The value is the name of a
variable whose value will be moved to vname. The original variable will
be unset. Cannot be used with any other options.
-M
Use the character mapping mapping such as
tolower and toupper when assigning a value to each of the
specified operands. When mapping is specified and there are not
operands, all variables that use this mapping are written to standard output.
When mapping is omitted and there are no operands, all mapped variables
are written to standard output.
-n
Declares vname to be a reference to the variable
whose name is defined by the value of variable vname. This is usually
used to reference a variable inside a function whose name has been passed as
an argument.
-p
The name, attributes and values for the given
vname are written on standard output in a form that can be used as
shell input. If +p is specified, then the values are not
displayed.
-R
Right justify and fill with leading blanks. If
n
is
non-zero, it defines the width of the field, otherwise it is
determined by the width of the value of first assignment. The field is left
filled with blanks or truncated from the end if the variable is reassigned.
The
-L option is turned off.
The -i attribute cannot be specified with -R.
-r
The specified vnames are marked read-only and
these names cannot be changed by subsequent assignment.
-S
When used within the assign_list of a type
definition, it causes the specified sub-variable to be shared by all instances
of the type. When used inside a function defined with the function
reserved word, the specified variables will have function static scope.
Otherwise, the variable is unset prior to processing the assignment
list.
-t
Tags the variables. Tags are user definable and have no
special meaning to the shell.
-T
If followed by tname, it creates a type named by
tname using the compound assignment assign_list to tname.
Otherwise, it writes all the type definitions to standard output.
-u
When given along with -i specifies unsigned
integer. Otherwise, all lower-case characters are converted to upper-case. The
lower-case option, -l, is turned off. Equivalent to -M
toupper.
-x
The specified vnames are marked for automatic
export to the environment of subsequently-executed commands. Variables whose
names contain a . cannot be exported.
-X
Declares vname to be a double precision floating
point number and expands using the %a format of ISO-C99. If n is
non-zero, it defines the number of hex digits after the radix point that is
used when expanding vname. The default is 10.
-Z
Right justify and fill with leading zeros if the first
non-blank character is a digit and the
-L option has not been set.
Remove leading zeros if the
-L option is also set. If
n is
non-zero, it defines the width of the field, otherwise it is determined
by the width of the value of first assignment.
The -i attribute cannot be specified with -Z.
ulimit [-HSacdfmnpstv] [
limit]
Set or display a resource limit. Many systems do not
support one or more of these limits. The limit for a specified resource is set
when
limit is specified. The value of
limit can be a number in
the unit specified with each resource, or the value unlimited. When more than
one resource is specified, then the limit name and unit is printed before the
value.
If no option is specified, -f is assumed.
The following are the available resource limits:
-a
Lists all of the current resource limits.
-c
The number of 512-byte blocks on the size of core
dumps.
-d
The number of Kbytes on the size of the data area.
-f
The number of 512-byte blocks on files that can be
written by the current process or by child processes (files of any size can be
read).
-H
Specifies a hard limit for the specified resource.
A hard limit cannot be increased once it is set.
If neither the -H nor -S option is specified, the
limit applies to both. The current resource limit is printed when
limit is omitted. In this case, the soft limit is printed unless
-H is specified.
-m
The number of Kbytes on the size of physical
memory.
-n
The number of file descriptors plus 1.
-p
The number of 512-byte blocks for pipe buffering.
-s
The number of Kbytes on the size of the stack area.
-S
Specifies a soft limit for the specified resource.
A soft limit can be increased up to the value of the hard
limit.
If neither the -H nor -S option is specified, the
limit applies to both. The current resource limit is printed when
limit is omitted. In this case, the soft limit is printed unless
-H is specified.
-t
The number of CPU seconds to be used by each
process.
-v
The number of Kbytes for virtual memory.
umask
[-S][mask]
The user file-creation mask is set to
mask.
mask can either be an octal number or a symbolic value as described in
chmod(1).
If a symbolic value is specified, the new umask value is
the complement of the result of applying mask to the complement of
the previous umask value. If mask is omitted, the current
value of the mask is printed. The -S option causes the mode to be
printed as a symbolic value. Otherwise, the mask is printed in octal.
See umask(2)
+unalias [-a] name
The aliases specified by the list of names are
removed from the alias list. The -a option causes all the aliases to be
unset.
+unset [-fnv] vname
The variables specified by the list of vnames are
unassigned, i.e., their values and attributes are erased. Read-only variables
cannot be unset. If the -f option is set, then the names refer to
function names. If the -v option is set, then the names refer to
variable names. The -f option overrides -v. If -n is set
and name is a name reference, then name is unset rather than the
variable that it references. The default is equivalent to -v. Unsetting
LINENO, MAILCHECK, OPTARG, OPTIND, RANDOM,
SECONDS, TMOUT, and _ removes their special meaning even
if they are subsequently assigned to.
wait [job]
Wait for the specified job and report its termination
status. If job is not specified, then all currently active child
processes are waited for. The exit status from this command is that of the
last process waited for if job is specified; otherwise it is zero. See
Jobs for a description of the format of job.
whence [-afpv] name ...
For each name, indicate how it would be
interpreted if used as a command name. The -v option produces a more
verbose report. The -f option skips the search for functions. The
-p option does a path search for name even if name is an alias,
a function, or a reserved word. The -a option is similar to the -v
option but causes all interpretations of the specified name to be
reported.
If the shell is invoked by exec(2), and the first character of argument
zero ($0) is -, then the shell is assumed to be a login shell
and commands are read from /etc/profile and then from either
.profile in the current directory or $HOME/.profile, if either
file exists. Next, for interactive shells, commands are read first from
/etc/ksh.kshrc, and then from the file named by performing parameter
expansion, command substitution, and arithmetic substitution on the value of
the environment variable ENV if the file exists. If the -s
option is not present and arg and a file by the name of arg
exists, then it reads and executes this script. Otherwise, if the first
arg does not contain a /, a path search is performed on the
first arg to determine the name of the script to execute. The script
arg must have execute permission and any setuid and
setgid settings are ignored. If the script is not found on the path,
arg is processed as if it named a built-in command or function.
Commands are then read as described, and the following options are
interpreted by the shell when it is invoked:
-c
If the -c option is present, then commands are
read from the first arg. Any remaining arguments become positional
parameters starting at 0.
-D
A list of all double quoted strings that are preceded by
a $ is printed on standard output and the shell exits. This set of
strings is subject to language translation when the locale is not C or POSIX.
No commands are executed.
-E
Reads the file named by the ENV variable or by
$HOME/.kshrc if not defined after the profiles.
-i
If the -i option is present or if the shell input
and output are attached to a terminal (as told by tcgetattr(3C), this
shell is interactive. In this case TERM is ignored (so that kill
0 does not kill an interactive shell) and INTR is caught and
ignored (so that wait is interruptible). In all cases, QUIT is ignored
by the shell.
-P
If -P or -o profile is present, the shell
is a profile shell (see pfexec(1)).
-R filename
The -R filename option is used to generate
a cross reference database that can be used by a separate utility to find
definitions and references for variables and commands.
-r
If the -r option is present, the shell is a
restricted shell.
-s
If the -s option is present or if no arguments
remain, then commands are read from the standard input. Shell output, except
for the output of the Special Commands listed, is written to file
descriptor 2.
The remaining options and arguments are described under the
set command. An optional - as the first argument is
ignored.
rksh93 is used to set up login names and execution environments whose
capabilities are more controlled than those of the standard shell.
The actions of rksh93 are identical to those of
ksh93, except that the following are disallowed:
- o
- Unsetting the restricted option
- o
- Changing directory. See cd(1).
- o
- Setting or unsetting the value or attributes of SHELL, ENV,
FPATH, or PATH
- o
- Specifying path or command names containing /,
- o
- Redirecting output (>, >|, <>, and
>>).
- o
- Adding or deleting built-in commands.
- o
- Using command -p to invoke a command.
These restrictions are enforced after .profile and the
ENV files are interpreted.
When a command to be executed is found to be a shell procedure,
rksh93 invokes ksh93 to execute it. Thus, it is possible to
provide to the end-user shell procedures that have access to the full power
of the standard shell, while imposing a limited menu of commands. This
scheme assumes that the end-user does not have write and execute permissions
in the same directory. The net effect of these rules is that the writer of
the .profile has complete control over user actions, by performing
guaranteed setup actions and leaving the user in an appropriate directory
(probably not the login directory). The system administrator often sets up a
directory of commands, for example, /usr/rbin, that can be safely
invoked by rksh.