=over

=item getpgrp PID
X<getpgrp> X<group>

Returns the current process group for the specified PID.  Use
a PID of C<0> to get the current process group for the
current process.  Will raise an exception if used on a machine that
doesn't implement L<getpgrp(2)>.  If PID is omitted, returns the process
group of the current process.

Some very old machines may not support C<PID != 0> and will throw an
exception if C<PID != 0>.

Portability issues: L<perlport/getpgrp>.

=back