bsd man page for setregid

SETREGID(2)							System Calls Manual						       SETREGID(2)

NAME
       setregid - set real and effective group ID

SYNOPSIS
       setregid(rgid, egid)
       int rgid, egid;

DESCRIPTION
       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 parame-
       ter.

RETURN VALUE
       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 super-user and a change other than changing the effective group-id to the real group-id was
		      specified.

SEE ALSO
       getgid(2), setreuid(2), setgid(3)

4.2 Berkeley Distribution					   May 15, 1985 						       SETREGID(2)