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chmod(2) [ultrix man page]

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)

Check Out this Related Man Page

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)
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