chmod(2)                                                 chmod(2)



NAME
     chmod, fchmod - change mode of file

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

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

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

DESCRIPTION
     chmod sets the access-permission portion of the named file's
     mode according to the bit pattern contained in mode.  The
     path argument points to a pathname of a file.

     Access-permission bits are interpreted as follows:

          04000
               Set effective user ID on execution.

          02000
               Set effective group ID on execution.

          01000
               Save text image after execution.

          00400
               Read by owner.

          00200
               Write by owner.

          00100
               Execute (search if a directory) by owner.

          00070
               Read, write, execute (search) by group.

          00007
               Read, write, execute (search) by others.

     To change the mode of a file, the effective user ID of the
     calling process must match the owner of the file or be the
     superuser.

     If the effective user ID of the process is not the
     superuser, mode bit 01000 (save text image after execution)
     is cleared.



January 1992                                                    1

chmod(2)                                                 chmod(2)



     If the effective user ID of the process is not the superuser
     and the effective group ID of the process does not match the
     group ID of the file, mode bit 02000 (set the effective
     group ID on execution) is cleared.

     If an executable file is prepared for sharing (refer to the
     -n option for the cc(1) command), then mode bit 01000
     prevents the system from abandoning the swap-space image of
     the program-text portion of the file when its last user
     terminates.  Thus, when the next user of the file executes
     it, the text need not be read from the file system but can
     simply be swapped in, saving time.

     Changing the owner of a file turns off mode bit 04000 (set
     user ID), unless the superuser does it.  Changing this bit
     makes the system somewhat more secure at the expense of a
     degree of compatibility.

STATUS MESSAGES AND VALUES
     On successful completion, a value of 0 is returned.
     Otherwise, a value of -1 is returned and errno is set to
     indicate the error.

     The chmod command will fail and the file mode will be
     unchanged if one or more of the following conditions is
     true:

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

     EFAULT
          The path points outside the allocated address space of
          the process.

     ELOOP
          Too many symbolic links were encountered in translating
          a pathname.

     ENAMETOOLONG
          A component of a pathname exceeded NAME_MAX characters,
          or an entire pathname exceeded PATH_MAX.

     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.



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chmod(2)                                                 chmod(2)



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

SEE ALSO
     chown(2), mknod(2), open(2), stat(2), umask(2)

     chmod(1) in A/UX Command Reference
















































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