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SETREGID(2)                 BSD System Calls Manual                SETREGID(2)

     setregid -- set real and effective group ID

     Standard C Library (libc, -lc)

     #include <unistd.h>

     setregid(gid_t rgid, gid_t egid);

     The real and effective group ID's of the current process are set to the
     arguments.  Unprivileged users may change the real group ID to the effec-tive effective
     tive group ID and vice-versa; only the super-user 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
     effective group IDs in set-group-ID programs to temporarily relinquish
     the set-group-ID value.  This function did not work correctly; its pur-pose purpose
     pose is now better served by the use of the setegid() function (see

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

     The setregid() function returns the value 0 if successful; otherwise the
     value -1 is returned and the global variable errno is set to indicate the

     [EPERM]            The current process is not the super-user and a change
                        other than changing the effective group-id to the real
                        group-id was specified.

     getgid(2), issetugid(2), setegid(2), setgid(2), setuid(2)

     The setregid() system call appeared in 4.2BSD.

BSD                             April 16, 1994                             BSD