CHMOD(2)							System Calls Manual							  CHMOD(2)

NAME

       chmod - change mode of file

SYNOPSIS

       chmod(path, mode)
       char *path;
       int mode;

       fchmod(fd, mode)
       int fd, mode;

DESCRIPTION

       The  file  whose  name  is  given by path or referenced by the descriptor fd has its mode changed to mode.  Modes are constructed by or'ing
       together some combination of the following, defined in <sys/inode.h>:

	      ISUID   04000   set user ID on execution
	      ISGID   02000   set group ID on execution
	      ISVTX   01000   `sticky bit' (see below)
	      IREAD   00400   read by owner
	      IWRITE  00200   write by owner
	      IEXEC   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 ISVTX (the `sticky bit') 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 on executable files is
       restricted to the super-user.

       If mode ISVTX (the `sticky bit') is set on a directory, an unprivileged user may not delete or rename files of other users in  that  direc-
       tory.  For more details of the properties of the sticky bit, see sticky(8).

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

       Writing	or changing the owner of a file turns off the set-user-id and set-group-id bits unless the user is the super-user.  This makes the
       system somewhat more secure by protecting set-user-id (set-group-id) files from remaining set-user-id (set-group-id) if they are  modified,
       at the expense of a degree of compatibility.

RETURN VALUE

       Upon successful completion, a value of 0 is returned.  Otherwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS

       Chmod will fail and the file mode will be unchanged if:

       [ENOTDIR]      A component of the path prefix is not a directory.

       [EINVAL]       The pathname contains a character with the high-order bit set.

       [ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.

       [ENOENT]       The named file does not exist.

       [EACCES]       Search permission is denied for a component of the path prefix.

       [ELOOP]	      Too many symbolic links were encountered in translating the pathname.

       [EPERM]	      The effective user ID does not match the owner of the file and the effective user ID is not the super-user.

       [EROFS]	      The named file resides on a read-only file system.

       [EFAULT]       Path points outside the process's allocated address space.

       [EIO]	      An I/O error occurred while reading from or writing to the file system.

       Fchmod will fail if:

       [EBADF]	      The descriptor is not valid.

       [EINVAL]       Fd refers to a socket, not to a file.

       [EROFS]	      The file resides on a read-only file system.

       [EIO]	      An I/O error occurred while reading from or writing to the file system.

SEE ALSO

       chmod(1), open(2), chown(2), stat(2), sticky(8)

4th Berkeley Distribution					   May 13, 1986 							  CHMOD(2)