chmod(2)							System Calls Manual							  chmod(2)

Name
       chmod, fchmod - change mode of file

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

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

       fchmod(fd, mode)
       int fd;
       mode_t mode;

Description
       The  file  whose  name is provided by path or referenced by the descriptor fd has its mode changed to mode.  Modes are constructed by ORing
       combinations of the following:

       S_ISUID	   - 04000  set user ID on execution

       S_ISGID	   - 02000  set group ID on execution

       S_ISVTX	   - 01000  save text image after execution

       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 (search) by group

       S_IRWXO	   - 00007  read, write, execute (search) by others

       If an executable file is set up for sharing (the default), the mode S_ISVTX prevents the system from abandoning the swap-space image of the
       program-text portion of the file when its last user terminates.	The ability to set this bit is restricted to the superuser.

       If  the	mode  S_ISVTX  (sticky	bit)  is set on a directory, an unprivileged user cannot delete or the rename files of other users in that
       directory.  For more information on the sticky bit, see

       Only the owner of a file or the superuser can change the mode.

       Writing a file or changing the owner of a file clears the set-user-id and set-group-id bits of that file. Turning off  these  bits  when  a
       file is written or its owner changed protects the file from remaining set-user-id or set-group-id after being modified. If a file, specifi-
       cally a program, remained set-user-id or set-group-id after being modified, that file could allow unauthorized access  to  other  files	or
       accounts.

Environment
   System Five
       ELOOP is a possible error condition.

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

Diagnostics
       The system call fails and the file mode remains unchanged under the following conditions:

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

       [EFAULT]       The path argument points outside the process's allocated address space.

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

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

       [ENAMETOOLONG] A pathname component exceeds 255 characters, or an entire pathname exceeds 1023 characters.

       [ENOENT]       The named file does not exist.

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

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

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

       [ESTALE]       The  file  handle  given in the argument is invalid.  Either the file referred to by that file handle no longer exists or it
		      has been revoked.

       The system call fails under the following conditions:

       [EBADF]	      The descriptor is not valid.

       [EINVAL]       The fd refers to a socket, not to a file.

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

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

       [ETIMEDOUT]    A connect request or remote file operation failed because the connected party did not respond after a period of time  deter-
		      mined by the communications protocol.

See Also
       open(2), chown(2)

																	  chmod(2)