DB<1> b work
  DB<2> c
main::work(test.pl:12):         $pid = open PROC, 
main::work(test.pl:13):     'perl -le"$|=1; print and select(undef,undef,undef,0.1) for 1 .. 1000" |'
main::work(test.pl:14):                 or die $!;
  DB<2> n
  DB<2> x $pid
0  9940
  DB<3> x $$                                    
0  9850

##</code><code>##

/tmp$ pstree -apA 9850
perl,9850 -d -I /etc/perl -I /usr/local/lib/perl/5.10.1 -I /usr/local/share/perl/5.10.1 -I
  |-sh,9940 -c perl -le"$|=1; print and select(undef,undef,undef,0.1) for 1 .. 1000"
  |   `-perl,9941 -le$|=1; print and select(undef,undef,undef,0.1) for 1 .. 1000
  `-{perl},9939