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  10 .TH TAIL 1 "Jul 13, 2005"
  11 .SH NAME
  12 tail \- deliver the last part of a file
  13 .SH SYNOPSIS
  14 .LP
  15 .nf
  16 \fB/usr/bin/tail\fR [\(+-s \fInumber\fR [lbcr]] [\fIfile\fR]
  17 .fi
  18 
  19 .LP
  20 .nf
  21 \fB/usr/bin/tail\fR [\fB-lbcr\fR] [\fIfile\fR]
  22 .fi
  23 
  24 .LP
  25 .nf
  26 \fB/usr/bin/tail\fR [\(+- \fInumber\fR [lbcf]] [\fIfile\fR]
  27 .fi
  28 
  29 .LP
  30 .nf
  31 \fB/usr/bin/tail\fR [\fB-lbcf\fR] [\fIfile\fR]
  32 .fi
  33 
  34 .LP
  35 .nf
  36 \fB/usr/xpg4/bin/tail\fR [\fB-f\fR | \fB-r\fR] [\fB-c\fR \fInumber\fR | \fB-n\fR \fInumber\fR] [\fIfile\fR]
  37 .fi
  38 
  39 .LP
  40 .nf
  41 \fB/usr/xpg4/bin/tail\fR [\(+- \fInumber\fR [l | b | c] [f]] [\fIfile\fR]
  42 .fi
  43 
  44 .LP
  45 .nf
  46 \fB/usr/xpg4/bin/tail\fR [\(+- \fInumber\fR [l] [f | r]] [\fIfile\fR]
  47 .fi
  48 
  49 .SH DESCRIPTION
  50 .sp
  51 .LP
  52 The \fBtail\fR utility copies the named file to the standard output beginning
  53 at a designated place. If no file is named, the standard input is used.
  54 .sp
  55 .LP
  56 Copying begins at a point in the file indicated by the \fB-c\fR\fInumber\fR,
  57 \fB-n\fR\fInumber\fR, or \fB\(+-\fR\fInumber\fR options (if \fB+\fR\fInumber\fR
  58 is specified, begins at distance number from the beginning; if
  59 \fB-\fR\fInumber\fR is specified, from the end of the input; if \fInumber\fR is
  60 \fINULL\fR, the value \fB10\fR is assumed). \fInumber\fR is counted in units of
  61 lines or byte according to the \fB-c\fR \fB or \fR \fB-n\fR options, or lines,
  62 blocks, or bytes, according to the appended option \fBl\fR, \fBb\fR, or
  63 \fBc\fR. When no units are specified, counting is by lines.
  64 .SH OPTIONS
  65 .sp
  66 .LP
  67 The following options are supported for both \fB/usr/bin/tail\fR and
  68 \fB/usr/xpg4/bin/tail\fR. The \fB-r\fR and \fB-f\fR options are mutually
  69 exclusive. If both are specified on the command line, the \fB-f\fR option is
  70 ignored.
  71 .sp
  72 .ne 2
  73 .na
  74 \fB\fB-b\fR \fR
  75 .ad
  76 .RS 7n
  77 Units of blocks.
  78 .RE
  79 
  80 .sp
  81 .ne 2
  82 .na
  83 \fB\fB-c\fR \fR
  84 .ad
  85 .RS 7n
  86 Units of bytes.
  87 .RE
  88 
  89 .sp
  90 .ne 2
  91 .na
  92 \fB\fB-f\fR \fR
  93 .ad
  94 .RS 7n
  95 Follow. If the input-file is not a pipe, the program does not terminate after
  96 the line of the input-file has been copied, but enters an endless loop, wherein
  97 it sleeps for a second and then attempts to read and copy further records from
  98 the input-file. Thus it can be used to monitor the growth of a file that is
  99 being written by some other process.
 100 .RE
 101 
 102 .sp
 103 .ne 2
 104 .na
 105 \fB\fB-l\fR \fR
 106 .ad
 107 .RS 7n
 108 Units of lines.
 109 .RE
 110 
 111 .sp
 112 .ne 2
 113 .na
 114 \fB\fB-r\fR \fR
 115 .ad
 116 .RS 7n
 117 Reverse. Copies lines from the specified starting point in the file in reverse
 118 order. The default for \fBr\fR is to print the entire file in reverse order.
 119 .RE
 120 
 121 .SS "/usr/xpg4/bin/tail"
 122 .sp
 123 .LP
 124 The following options are supported for \fB/usr/xpg4/bin/tail\fR only:
 125 .sp
 126 .ne 2
 127 .na
 128 \fB\fB-c\fR \fInumber\fR \fR
 129 .ad
 130 .RS 14n
 131 The \fInumber\fR option-argument must be a decimal integer whose sign affects
 132 the location in the file, measured in bytes, to begin the copying:
 133 .sp
 134 .ne 2
 135 .na
 136 \fB\fB+\fR \fR
 137 .ad
 138 .RS 9n
 139 Copying starts relative to the beginning of the file.
 140 .RE
 141 
 142 .sp
 143 .ne 2
 144 .na
 145 \fB\fB\(mi\fR \fR
 146 .ad
 147 .RS 9n
 148 Copying starts relative to the end of the file.
 149 .RE
 150 
 151 .sp
 152 .ne 2
 153 .na
 154 \fBnone\fR
 155 .ad
 156 .RS 9n
 157 Copying starts relative to the end of the file.
 158 .RE
 159 
 160 The origin for counting is 1; that is, \fB\fR\fB-c\fR\fB+1\fR represents the
 161 first byte of the file, \fB\fR\fB-c\fR\fB\(mi1\fR the last.
 162 .RE
 163 
 164 .sp
 165 .ne 2
 166 .na
 167 \fB\fB-n\fR \fInumber\fR \fR
 168 .ad
 169 .RS 14n
 170 Equivalent to \fB-c\fR\fInumber,\fR except the starting location in the file is
 171 measured in lines instead of bytes. The origin for counting is \fB1\fR. That
 172 is, \fB-n\fR\fB+1\fR represents the first line of the file, \fB-n\fR\fB\(mi1\fR
 173 the last.
 174 .RE
 175 
 176 .SH OPERANDS
 177 .sp
 178 .LP
 179 The following operand is supported:
 180 .sp
 181 .ne 2
 182 .na
 183 \fB\fIfile\fR \fR
 184 .ad
 185 .RS 9n
 186 A path name of an input file. If no \fIfile\fR operands are specified, the
 187 standard input is used.
 188 .RE
 189 
 190 .SH USAGE
 191 .sp
 192 .LP
 193 See \fBlargefile\fR(5) for the description of the behavior of \fBtail\fR when
 194 encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).
 195 .SH EXAMPLES
 196 .LP
 197 \fBExample 1 \fRUsing the tail Command
 198 .sp
 199 .LP
 200 The following command prints the last ten lines of the file \fBfred\fR,
 201 followed by any lines that are appended to \fBfred\fR between the time
 202 \fBtail\fR is initiated and killed.
 203 
 204 .sp
 205 .in +2
 206 .nf
 207 example% \fBtail -f fred\fR
 208 .fi
 209 .in -2
 210 .sp
 211 
 212 .sp
 213 .LP
 214 The next command prints the last 15 bytes of the file \fBfred\fR, followed by
 215 any lines that are appended to \fBfred\fR between the time \fBtail\fR is
 216 initiated and killed:
 217 
 218 .sp
 219 .in +2
 220 .nf
 221 example% \fBtail -15cf fred\fR
 222 .fi
 223 .in -2
 224 .sp
 225 
 226 .SH ENVIRONMENT VARIABLES
 227 .sp
 228 .LP
 229 See \fBenviron\fR(5) for descriptions of the following environment variables
 230 that affect the execution of \fBtail\fR: \fBLANG\fR, \fBLC_ALL\fR,
 231 \fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
 232 .SH EXIT STATUS
 233 .sp
 234 .LP
 235 The following exit values are returned:
 236 .sp
 237 .ne 2
 238 .na
 239 \fB\fB0\fR \fR
 240 .ad
 241 .RS 7n
 242 Successful completion.
 243 .RE
 244 
 245 .sp
 246 .ne 2
 247 .na
 248 \fB\fB>0\fR \fR
 249 .ad
 250 .RS 7n
 251 An error occurred.
 252 .RE
 253 
 254 .SH ATTRIBUTES
 255 .sp
 256 .LP
 257 See \fBattributes\fR(5) for descriptions of the following attributes:
 258 .SS "/usr/bin/tail"
 259 .sp
 260 
 261 .sp
 262 .TS
 263 box;
 264 c | c
 265 l | l .
 266 ATTRIBUTE TYPE  ATTRIBUTE VALUE
 267 _
 268 CSI     Enabled
 269 .TE
 270 
 271 .SS "/usr/xpg4/bin/tail"
 272 .sp
 273 
 274 .sp
 275 .TS
 276 box;
 277 c | c
 278 l | l .
 279 ATTRIBUTE TYPE  ATTRIBUTE VALUE
 280 _
 281 CSI     Enabled
 282 _
 283 Interface Stability     Standard
 284 .TE
 285 
 286 .SH SEE ALSO
 287 .sp
 288 .LP
 289 \fBcat\fR(1), \fBhead\fR(1), \fBmore\fR(1), \fBpg\fR(1), \fBdd\fR(1M),
 290 \fBattributes\fR(5), \fBenviron\fR(5), \fBlargefile\fR(5), \fBstandards\fR(5)
 291 .SH NOTES
 292 .sp
 293 .LP
 294 Piped tails relative to the end of the file are stored in a buffer, and thus
 295 are limited in length. Various kinds of anomalous behavior can happen with
 296 character special files.