SETREGID(2) BSD System Calls Manual SETREGID(2)
setregid -- set real and effective group ID
Standard C Library (libc, -lc)
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 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, and its
purpose 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