SETREGID(2)               OpenBSD Programmer's Manual              SETREGID(2)

NAME
     setregid - set real and effective group IDs

SYNOPSIS
     #include <unistd.h>

     int
     setregid(gid_t rgid, gid_t egid);

DESCRIPTION
     The real and effective group IDs of the current process are set according
     to the arguments.  If the real group ID is changed, the saved group ID is
     changed to the new value of the effective group ID.

     Unprivileged users may change either group ID to the current value of the
     real, effective, or saved group ID.  Only the superuser may make other
     changes.

     Supplying a value of -1 for either the real or effective group ID forces
     the system to substitute the current ID in place of the -1 parameter.

     The setregid() function was intended to allow swapping the real and ef-
     fective group IDs in set-group-ID programs to temporarily relinquish the
     set-group-ID value.  This purpose is now better served by the use of the
     setegid() function (see setuid(2)).

     When setting the real and effective group IDs to the same value, the
     setgid() function is preferred.

RETURN VALUES
     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
     [EPERM]       The current process is not the superuser and a change other
                   than changing the effective group ID to the real group ID
                   was specified.

SEE ALSO
     getgid(2), setegid(2), setgid(2), setresgid(2), setuid(2)

STANDARDS
     The setregid() function conforms to the IEEE Std 1003.1-2001 (``POSIX'')
     and X/Open Portability Guide Issue 4.3 (``XPG4.3'').  specifications.

     Note, however, that prior to IEEE Std 1003.1-2001 (``POSIX''), the
     setregid() function was not a part of the IEEE Std 1003.1 (``POSIX'')
     specification.  As a result, it may not be implemented on all systems.

HISTORY
     The setregid() function call appeared in 4.2BSD.  A semantically differ-
     ent version appeared in 4.4BSD.  The current version, with the original
     semantics restored, appeared in OpenBSD 3.3.

CAVEATS
     The setregid() function predates POSIX saved group IDs.  This implementa-
     tion changes the saved group ID to the new value of the effective group
     ID if the real group ID is changed.  Other implementations may behave
     differently.

OpenBSD 4.0                    January 29, 2003                              1
