4.3BSD - /usr/man/cat2/setregid.0

SETREGID(2)                                                        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
       parameter.

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)