NAME

chmod − change mode of file

SYNOPSIS

chmod(name, mode)
char \(**name;

DESCRIPTION

The file whose name is given as the null-terminated string pointed to by name has its mode changed to mode. Modes are constructed by oring together some combination of the following:

 04000 set user ID on execution
 02000 set group ID on execution
 01000 save text image after execution
 00400 read by owner
 00200 write by owner
 00100 execute (search on directory) by owner
 00070 read, write, execute (search) by group
 00007 read, write, execute (search) by others

If an executable file is set up for sharing (this is the default) then mode 1000 prevents the system from abandoning the swap-space image of the program-text portion of the file when its last user terminates.  Ability to set this bit is restricted to the super-user since swap space is consumed by the images.  See sticky(8).

Only the owner of a file (or the super-user) may change the mode.  Only the super-user can set the 1000 mode. 

On some systems, writing or changing the owner of a file turns off the set-user-id bit.  This makes the system somewhat more secure by protecting set-user-id files from remaining set-user-id if they are modified, at the expense of a degree of compatibility. 

SEE ALSO

chmod(1)

DIAGNOSTIC

Zero is returned if the mode is changed; −1 is returned if name cannot be found or if the current user is neither the owner of the file nor the super-user. 

ASSEMBLER (PDP-11)

(chmod = 15.) 
sys chmod; name; mode

4th Berkeley Distribution  —  %W%%Q%%Y%