CHMOD(2)							System Calls Manual							  CHMOD(2)

NAME

       chmod - change mode of file

SYNOPSIS

       #include <sys/types.h>
       #include <sys/stat.h>

       int chmod(const char *path, mode_t mode)

DESCRIPTION

       The  file  whose name is given by path has its mode changed to mode.  Modes are constructed by or'ing together some combination of the fol-
       lowing, defined in <sys/stat.h>:

	      S_ISUID  04000   set user ID on execution
	      S_ISGID  02000   set group ID on execution
	      S_ISVTX  01000   `sticky bit' (see below)
	      S_IRWXU  00700   read, write, execute by owner
	      S_IRUSR  00400   read by owner
	      S_IWUSR  00200   write by owner
	      S_IXUSR  00100   execute (search on directory) by owner
	      S_IRWXG  00070   read, write, execute by group
	      S_IRGRP  00040   read by group
	      S_IWGRP  00020   write by group
	      S_IXGRP  00010   execute (search on directory) by group
	      S_IRWXO  00007   read, write, execute by others
	      S_IROTH  00004   read by others
	      S_IWOTH  00002   write by others
	      S_IXOTH  00001   execute (search on directory) by others

       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.  (Minix-vmd)

       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.

       [ENAMETOOLONG] The path name exceeds PATH_MAX 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.  (Minix-vmd)

       [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.

SEE ALSO

       chmod(1), open(2), chown(2), stat(2).

NOTES

       The sticky bit was historically used to lock important executables into memory.

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