SETFACL(1) User Commands SETFACL(1)

setfacl - modify the Access Control List (ACL) for a file or files 

setfacl [-r] -s acl_entries file


setfacl [-r] -md acl_entries file


setfacl [-r] -f acl_file file

For each file specified, setfacl either replaces its entire ACL, including the default ACL on a directory, or it adds, modifies, or deletes one or more ACL entries, including default entries on directories.

The setfacl utility can only manipulate POSIX-draft ACLs. See acl(5) for a description of the difference between the older POSIX-draft ACLs and the newer NFSv4 ACLs. The chmod(1) utility can be used to manipulate ACLs on all types of file system.

When the setfacl command is used, it can result in changes to the file permission bits. When the user ACL entry for the file owner is changed, the file owner class permission bits are modified. When the group ACL entry for the file group class is changed, the file group class permission bits are modified. When the other ACL entry is changed, the file other class permission bits are modified.

If you use the chmod(1) command to change the file group owner permissions on a file with ACL entries, both the file group owner permissions and the ACL mask are changed to the new permissions. Be aware that the new ACL mask permissions can change the effective permissions for additional users and groups who have ACL entries on the file.

A directory can contain default ACL entries. If a file or directory is created in a directory that contains default ACL entries, the newly created file has permissions generated according to the intersection of the default ACL entries and the permissions requested at creation time. The umask(1) are not applied if the directory contains default ACL entries. If a default ACL is specified for a specific user (or users), the file has a regular ACL created. Otherwise, only the mode bits are initialized according to the intersection described above. The default ACL should be thought of as the maximum discretionary access permissions that can be granted.

Use the setfacl command to set ACLs on files in a UFS file system, which supports POSIX-draft ACLS (or aclent_t style ACLs). Use the chmod command to set ACLs on files in a ZFS file system, which supports NFSv4-style ACLS (or ace_t style ACLs).

For the -m and -s options, acl_entries are one or more comma-separated ACL entries.

An ACL entry consists of the following fields separated by colons:

entry_type

Type of ACL entry on which to set file permissions. For example, entry_type can be user (the owner of a file) or mask (the ACL mask).

uid or gid

User name or user identification number. Or, group name or group identification number.

perms

Represents the permissions that are set on entry_type. perms can be indicated by the symbolic characters rwx or a number (the same permissions numbers used with the chmod command).

The following table shows the valid ACL entries (default entries can only be specified for directories):

ACL Entry Description
u[ser]::perms File owner permissions.
g[roup]::perms File group owner permissions.
o[ther]:perms Permissions for users other than the file owner or members of file group owner.
m[ask]:perms The ACL mask. The mask entry indicates the maximum permissions allowed for users (other than the owner) and for groups. The mask is a quick way to change permissions on all the users and groups.
u[ser]:uid:perms Permissions for a specific user. For uid, you can specify either a user name or a numeric UID.
g[roup]:gid:perms Permissions for a specific group. For gid, you can specify either a group name or a numeric GID.
d[efault]:u[ser]::perms Default file owner permissions.
d[efault]:g[roup]::perms Default file group owner permissions.
d[efault]:o[ther]:perms Default permissions for users other than the file owner or members of the file group owner.
d[efault]:m[ask]:perms Default ACL mask.
d[efault]:u[ser]:uid:perms Default permissions for a specific user. For uid, you can specify either a user name or a numeric UID.
d[efault]:g[roup]:gid:perms Default permissions for a specific group. For gid, you can specify either a group name or a numeric GID.

For the -d option, acl_entries are one or more comma-separated ACL entries without permissions. Notice that the entries for file owner, file group owner, ACL mask, and others can not be deleted.

The options have the following meaning:

-d acl_entries

Deletes one or more entries from the file. The entries for the file owner, the file group owner, and others can not be deleted from the ACL. Notice that deleting an entry does not necessarily have the same effect as removing all permissions from the entry.

-f acl_file

Sets a file's ACL with the ACL entries contained in the file named acl_file. The same constraints on specified entries hold as with the -s option. The entries are not required to be in any specific order in the file. Also, if you specify a dash (-) for acl_file, standard input is used to set the file's ACL.

The character # in acl_file can be used to indicate a comment. All characters, starting with the # until the end of the line, are ignored. Notice that if the acl_file has been created as the output of the getfacl(1) command, any effective permissions, which follow a #, are ignored.

-m acl_entries

Adds one or more new ACL entries to the file, and/or modifies one or more existing ACL entries on the file. If an entry already exists for a specified uid or gid, the specified permissions replace the current permissions. If an entry does not exist for the specified uid or gid, an entry is created. When using the -m option to modify a default ACL, you must specify a complete default ACL (user, group, other, mask, and any additional entries) the first time.

-r

Recalculates the permissions for the ACL mask entry. The permissions specified in the ACL mask entry are ignored and replaced by the maximum permissions necessary to grant the access to all additional user, file group owner, and additional group entries in the ACL. The permissions in the additional user, file group owner, and additional group entries are left unchanged.

-s acl_entries

Sets a file's ACL. All old ACL entries are removed and replaced with the newly specified ACL. The entries need not be in any specific order. They are sorted by the command before being applied to the file.

Required entries:

o
Exactly one user entry specified for the file owner.
o
Exactly one group entry for the file group owner.
o
Exactly one other entry specified.
If there are additional user and group entries:
o
Exactly one mask entry specified for the ACL mask that indicates the maximum permissions allowed for users (other than the owner) and groups.
o
Must not be duplicate user entries with the same uid.
o
Must not be duplicate group entries with the same gid.
If file is a directory, the following default ACL entries can be specified:
o
Exactly one default user entry for the file owner.
o
Exactly one default group entry for the file group owner.
o
Exactly one default mask entry for the ACL mask.
o
Exactly one default other entry.
There can be additional default user entries and additional default group entries specified, but there can not be duplicate additional default user entries with the same uid, or duplicate default group entries with the same gid.

Example 1 Adding read permission only

The following example adds one ACL entry to file abc, which gives user shea read permission only.


setfacl -m user:shea:r−− abc

Example 2 Replacing a file's entire ACL

The following example replaces the entire ACL for the file abc, which gives shea read access, the file owner all access, the file group owner read access only, the ACL mask read access only, and others no access.


setfacl -s user:shea:rwx,user::rwx,group::rw-,mask:r--,other:--- abc

Notice that after this command, the file permission bits are rwxr-----. Even though the file group owner was set with read/write permissions, the ACL mask entry limits it to have only read permission. The mask entry also specifies the maximum permissions available to all additional user and group ACL entries. Once again, even though the user shea was set with all access, the mask limits it to have only read permission. The ACL mask entry is a quick way to limit or open access to all the user and group entries in an ACL. For example, by changing the mask entry to read/write, both the file group owner and user shea would be given read/write access.

Example 3 Setting the same ACL on two files

The following example sets the same ACL on file abc as the file xyz.


getfacl xyz | setfacl -f − abc

/etc/passwd
password file

/etc/group

group file

chmod(1), getfacl(1), umask(1), aclcheck(3SEC), aclsort(3SEC), group(4), passwd(4), acl(5), attributes(5)
February 8, 2020