NAME

chmod − change mode

SYNOPSIS

chmod mode file ... 

HP-UX COMPATIBILITY

Level: HP-UX/NUCLEUS

Origin: System V

Native Language Support:
8−bit filenames.

DESCRIPTION

The permissions of the named files are changed according to mode, which may be absolute or symbolic. An absolute mode is an octal number constructed from the OR of the following modes:

4000 set user ID on execution

2000 set group ID on execution

1000 sticky bit, see chmod(2)

0400 read by owner

0200 write by owner

0100 execute (search in directory) by owner

0070 read, write, execute (search) by group

0007 read, write, execute (search) by others

A symbolic mode has the form:

[ who ] op permission [ op permission ]

The who part is a combination of the letters u (for user’s permissions), g (group) and o (other).  The letter a stands for ugo, the default if who is omitted. 

Op can be + to add permission to the file’s mode, − to take away permission, or = to assign permission absolutely (all other bits will be reset). 

Permission is any combination of the letters r (read), w (write), x (execute), s (set owner or group ID) and t (save text − sticky); u, g or o indicate that permission is to be taken from the current mode.  Omitting permission is only useful with = to take away all permissions. 

Multiple symbolic modes separated by commas may be given.  Operations are performed in the order specified.  The letter s is only useful with u or g and t only works with u. 

Only the owner of a file (or the super-user) may change its mode.  Only the super-user may set the sticky bit.  In order to set the group ID, the group of the file must correspond to your current group ID. 

EXAMPLES

The first example denies write permission to others, and the second makes a file executable (using symbolic mode):

chmod o−w file

chmod +x file

The first example below assigns read and execute permission to everybody, and sets the set-user-id bit.  The second assigns read and write permission to the file owner, and read permission to everybody else (using absolute mode):

chmod 4555 file

chmod 644 file

SEE ALSO

ls(1), chmod(2). 

Hewlett-Packard  —  last mod. May 11, 2021