libc/sys/chmod.2

         Copyright (c) 1980 Regents of the University of California.
 All rights reserved. The Berkeley software License Agreement
 specifies the terms and conditions for redistribution.

 @(#)chmod.2 6.2 (Berkeley) 05/22/85

 CHMOD 2 ""
C 4  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:


 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.

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.
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:
 15
[ENOTDIR]
A component of the path prefix is not a directory.
 15
[EINVAL]
The pathname contains a character with the high-order bit set.
 15
[ENAMETOOLONG]
A component of a pathname exceeded 255 characters,
or an entire path name exceeded 1023 characters.
 15
[ENOENT]
The named file does not exist.
 15
[EACCES]
Search permission is denied for a component of the path prefix.
 15
[ELOOP]
Too many symbolic links were encountered in translating the pathname.
 15
[EPERM]
The effective user ID does not match the owner of the file and
the effective user ID is not the super-user.
 15
[EROFS]
The named file resides on a read-only file system.
 15
[EFAULT]
 Path points outside the process's allocated address space.

 Fchmod will fail if:
 15
[EBADF]
The descriptor is not valid.
 15
[EINVAL]
 Fd refers to a socket, not to a file.
 15
[EROFS]
The file resides on a read-only file system.
 "SEE ALSO"
open(2), chown(2)