4.4BSD/usr/share/man/cat2/chmod.0

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

NNAAMMEE
     cchhmmoodd, ffcchhmmoodd - change mode of file

SSYYNNOOPPSSIISS
     ##iinncclluuddee <<ssyyss//ssttaatt..hh>>

     _i_n_t
     cchhmmoodd(_c_o_n_s_t _c_h_a_r _*_p_a_t_h, _m_o_d_e___t _m_o_d_e);

     _i_n_t
     ffcchhmmoodd(_i_n_t _f_d, _m_o_d_e___t _m_o_d_e);

DDEESSCCRRIIPPTTIIOONN
     The function cchhmmoodd() sets the file permission bits of the file specified
     by the pathname _p_a_t_h to _m_o_d_e. FFcchhmmoodd() sets the permission bits of the
     specified file descriptor _f_d. CChhmmoodd() verifies that the process owner
     (user) either owns the file specified by _p_a_t_h (or _f_d), or is the super-
     user.  A mode is created from _o_r _A_p _d permission bit masks defined in
     <_s_y_s_/_s_t_a_t_._h>:
           #define S_IRWXU 0000700    /* RWX mask for owner */
           #define S_IRUSR 0000400    /* R for owner */
           #define S_IWUSR 0000200    /* W for owner */
           #define S_IXUSR 0000100    /* X for owner */

           #define S_IRWXG 0000070    /* RWX mask for group */
           #define S_IRGRP 0000040    /* R for group */
           #define S_IWGRP 0000020    /* W for group */
           #define S_IXGRP 0000010    /* X for group */

           #define S_IRWXO 0000007    /* RWX mask for other */
           #define S_IROTH 0000004    /* R for other */
           #define S_IWOTH 0000002    /* W for other */
           #define S_IXOTH 0000001    /* X for other */

           #define S_ISUID 0004000    /* set user id on execution */
           #define S_ISGID 0002000    /* set group id on execution */
           #define S_ISVTX 0001000    /* save swapped text even after use */

     The ISVTX (the _s_t_i_c_k_y _b_i_t) indicates to the system which executable files
     are shareable (the default) and the system maintains the program text of
     the files in the swap area. The sticky bit may only be set by the super
     user on shareable executable files.

     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 directory. The
     sticky bit may be set by any user on a directory which the user owns or
     has appropriate permissions.  For more details of the properties of the
     sticky bit, see sticky(8).

     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 sys-
     tem 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.

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

EERRRROORRSS
     CChhmmoodd() 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]      _P_a_t_h points outside the process's allocated address space.

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

     FFcchhmmoodd() will fail if:

     [EBADF]       The descriptor is not valid.

     [EINVAL]      _F_d 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.

SSEEEE AALLSSOO
     chmod(1),  open(2),  chown(2),  stat(2),  sticky(8)

SSTTAANNDDAARRDDSS
     CChhmmoodd() is expected to conform to IEEE Std 1003.1-1988 (``POSIX'').

HHIISSTTOORRYY
     The ffcchhmmoodd() function call appeared in 4.2BSD.

4th Berkeley Distribution        June 4, 1993                                2