chmod(1)chmod(1)NAMEchmod - change file mode access permissions
SYNOPSIS
symbolic_mode_list file ...
Obsolescent form
numeric_mode file ...
DESCRIPTION
The command changes the permissions of one or more files according to
the value of symbolic_mode_list or numeric_mode. You can display the
current permissions for a file with the command (see ls(1)).
Only the owner of a file, or a user with appropriate privileges, can
change its mode.
Only a user having appropriate privileges can set (or retain, if previ‐
ously set) the sticky bit of a regular file.
If the sticky bit is set on a directory, files inside the directory may
be renamed or removed only by the owner of the file, the owner of the
directory, or the superuser (even if the modes of the directory would
otherwise allow such an operation).
In order to set the set-group-ID bit, the group of the file must corre‐
spond to your current group ID.
If is used on a symbolic link, the mode of the file referred to by the
link is changed.
Options
The command recognizes the following options:
Preserve any optional access control list (ACL) entries
associated with the file (HFS file systems only). By
default, in conformance with the IEEE Standard POSIX
1003.1-1988, optional HFS ACL entries are deleted. For
JFS ACLs, this option has no effect, because optional JFS
ACL entries are always preserved. For information about
access control lists, see acl(5) and aclv(5).
Recursively change the file mode bits.
For each file operand that names a directory, alters the
file mode bits of the named directory and all files and
subdirectories in the file hierarchy below it.
Operands
The command recognizes the following operands:
file Targe file for which the permissions are changes.
numeric-mode
Numeric value used to determine permission on a specified
file. See the section for more information.
symbolic-mode-list
List of operations used to determine permissions on a
specified file. See the section for more information.
Symbolic Mode List
A symbolic_mode_list is a comma-separated list of operations in the
following form. Whitespace is not permitted.
[who]op[permission
The variable fields can have the following values:
who One or more of the following letters:
Modify permissions for user (owner).
Modify permissions for group.
Modify permissions for others.
Modify permissions for all users
is equivalent to
op Required; one of the following symbols:
Add permission to the existing file mode
bits of who.
Delete permission from the existing file mode
bits of who.
Replace the existing mode bits of
who with permission.
permission One or more of the following letters:
Add or delete the read permission for
who.
Add or delete the write permission for
who.
Add or delete the execute file (search direc‐
tory) permission for
who.
Add or delete the set-owner-ID-on-file-execu‐
tion
or set-group-ID-on-file-execution per‐
mission for who. Useful only if or is
expressed or implied in who.
Add or delete the sticky bit permission.
Useful only if is expressed or implied
in who. See chmod(2).
Conditionally add or delete the execute/search
permission as follows:
· If file is a directory, add or delete
the search permission to the existing
file mode for who. (Same as
· If file is not a directory, and the
current file permissions include the
execute permission displays an or an
for at least one of user, group, or
other, then add or delete the execute
file permission for who.
· If file is not a directory, and no
execute permissions are set in the
current file mode, then do not change
any execute permission.
Or one only of the following letters:
Copy the current user permissions to
who.
Copy the current group permissions to
who.
Copy the current other permissions to
who.
The operations are performed in the order specified, and can override
preceding operations specified in the same command line.
If who is omitted, the and permissions are changed for all users if the
changes are permitted by the current file mode creation mask (see
umask(1)). The and permissions are changed as if was specified in who.
Omitting permission is useful only when used with to delete all permis‐
sions.
Numeric Mode (Obsolescent)
Absolute permissions can be set by specifying a numeric_mode, an octal
number constructed from the logical OR (sum) of the following mode
bits:
Miscellaneous mode bits:
Permission mode bits:
EXTERNAL INFLUENCES
Environment Variables
determines the language in which messages are displayed.
If is not specified or is null, it defaults to the value of If is not
specified or is null, it defaults to (see lang(5)).
If any internationalization variable contains an invalid setting, all
internationalization variables default to See environ(5).
International Code Set Support
Single- and multibyte character code sets are supported.
RETURN VALUE
Upon completion, returns one of the following values:
Successful completion.
An error condition occurred.
EXAMPLES
Deny write permission to others:
Make a file executable by everybody:
Assign read and execute permission to everybody, and set the set-user-
ID bit:
Assign read and write permission to the file owner, and read permission
to everybody else:
or the obsolescent form:
Traverse a directory subtree making all regular files readable by user
and group only, and all executables and directories executable (search‐
able) by everyone:
If the current value of is displays do not change write permission for
group) and the current permissions for file are displayed by as then
the command
sets the permissions to displayed by as
If the current value of is displays do not change write permission for
group) and the current permissions for file are displayed by as then
the command
sets the permissions to displayed by as
DEPENDENCIES
The option causes to fail on file systems that do not support ACLs.
AUTHOR
was developed by AT&T and HP.
SEE ALSOchacl(1), ls(1), umask(1), chmod(2), acl(5), aclv(5).
STANDARDS CONFORMANCEchmod(1)
