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CHMOD(2)			    Linux Programmer's Manual				 CHMOD(2)

       chmod, fchmod - change permissions of a file

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

       int chmod(const char *path, mode_t mode);
       int fchmod(int fildes, mode_t mode);

       The mode of the file given by path or referenced by fildes is changed.

       Modes are specified by or'ing the following:

	      S_ISUID	04000 set user ID on execution

	      S_ISGID	02000 set group ID on execution

	      S_ISVTX	01000 sticky bit

	      S_IRUSR (S_IREAD)
			00400 read by owner

			00200 write by owner

	      S_IXUSR (S_IEXEC)
			00100 execute/search by owner

	      S_IRGRP	00040 read by group

	      S_IWGRP	00020 write by group

	      S_IXGRP	00010 execute/search by group

	      S_IROTH	00004 read by others

	      S_IWOTH	00002 write by others

	      S_IXOTH	00001 execute/search by others

       The effective UID of the process must be zero or must match the owner of the file.

       If  the	effective UID of the process is not zero and the group of the file does not match
       the effective group ID of the process or one of its supplementary group IDs,  the  S_ISGID
       bit will be turned off, but this will not cause an error to be returned.

       Depending  on  the  file system, set user ID and set group ID execution bits may be turned
       off if a file is written.  On some file systems, only the super-user can  set  the  sticky
       bit,  which  may  have a special meaning.  For the sticky bit, and for set user ID and set
       group ID bits on directories, see stat(2).

       On NFS file systems, restricting the permissions will immediately influence  already  open
       files,  because the access control is done on the server, but open files are maintained by
       the client.  Widening the permissions may  be  delayed  for  other  clients  if	attribute
       caching is enabled on them.

       On success, zero is returned.  On error, -1 is returned, and errno is set appropriately.

       Depending  on  the file system, other errors can be returned.  The more general errors for
       chmod are listed below:

       EPERM  The effective UID does not match the owner of the file, and is not zero.

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

       EFAULT path points outside your accessible address space.

	      path is too long.

       ENOENT The file does not exist.

       ENOMEM Insufficient kernel memory was available.

	      A component of the path prefix is not a directory.

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

       ELOOP  Too many symbolic links were encountered in resolving path.

       EIO    An I/O error occurred.

       The general errors for fchmod are listed below:

       EBADF  The file descriptor fildes is not valid.

       EROFS  See above.

       EPERM  See above.

       EIO    See above.

       The chmod call conforms to SVr4, SVID, POSIX, X/OPEN, 4.4BSD.  SVr4 documents EINTR,  ENO-
       LINK  and  EMULTIHOP  returns,  but  no ENOMEM.	POSIX.1 does not document EFAULT, ENOMEM,
       ELOOP or EIO error conditions, or the macros S_IREAD, S_IWRITE and S_IEXEC.

       The fchmod call conforms to 4.4BSD and SVr4.  SVr4 documents additional EINTR and  ENOLINK
       error   conditions.    POSIX   requires	 the   fchmod	function   if  at  least  one  of
       _POSIX_MAPPED_FILES and _POSIX_SHARED_MEMORY_OBJECTS is defined, and documents  additional
       ENOSYS and EINVAL error conditions, but does not document EIO.

       POSIX and X/OPEN do not document the sticky bit.

       open(2), chown(2), execve(2), stat(2)

Linux 2.0.32				    1997-12-10					 CHMOD(2)
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