CHMOD(1)
NAME
chmod − change mode
USAGE
chmod mode files
DESCRIPTION
Chmod allows the named files to be 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 ]
Who is a combination of the letters u (for owner’s permissions), g (group), and o (other). The letter a stands for ugo. If who is omitted, the default is a, but the setting of the creation mask is taken into account. See umask (2) for further details on this.
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, or sticky). The u, g, or o indicate that permission is to be taken from the current mode. Omitting permission is only useful with an equal sign (=) 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.
EXAMPLES
To deny others write permission to file1, type the following command:
chmod o-w file1
To make file1 executable, specify this:
chmod +x file1
To allow the owner of file1 read, write, and execute permissions to that file, but the group and others only read permission, use the following command:
chmod 744 file1
CAUTIONS
Due to a feature of DOMAIN memory management, files must have read permission in order to be written to or executed. This means that DOMAIN/IX does not recognize execute-only or write-only files. For example, if you type chmod 111 foo, DOMAIN/IX automatically sets read permissions for the owner as follows:
-r-xr-xr-x 1 owner unix 5 May 22 11:47 foo
Also, if you type chmod 222 foo, DOMAIN/IX automatically sets read permissions for owner as follows:
-rw-rw-rw- 1 harper sys 5 May 22 11:50 foo Only the owner of a file (or the super-user)
may change its mode.