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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 effective 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
     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 standard setgid() function is pre-ferred. 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 error.

     [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

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