system('rm test?.out 2> /dev/null');
   print "   ------\n   test 1\n";
   $rc = system('/usr/bin/ps', '>' , 'test1.out', '&');
   print '   rc=',$rc,"\n";
   print "   test1.out not created\n" unless -e 'test1.out';
   print "   ------\n   test 2\n";
   $rc = system('/usr/bin/ps > test2.out &');
   print '   rc=',$rc,"\n";
   print "   test2.out not created\n" unless -e 'test2.out';
   print "   ------\n   test 3\n";
   $rc = system('/usr/bin/ps', '>' , 'test3.out');
   print '   rc=',$rc,"\n";
   print "   test3.out not created\n" unless -e 'test3.out';

##</code><code>##

   ------
   test 1
usage: ps [ -aAdeflcjLPy ] [ -o format ] [ -t termlist ]
        [ -u userlist ] [ -U userlist ] [ -G grouplist ]
        [ -p proclist ] [ -g pgrplist ] [ -s sidlist ]
  'format' is one or more of:
        user ruser group rgroup uid ruid gid rgid pid ppid pgid sid taskid
        pri opri pcpu pmem vsz rss osz nice class time etime stime
        f s c lwp nlwp psr tty addr wchan fname comm args projid project
   rc=256
   test1.out not created
   ------
   test 2
   rc=0
   ------
   test 3
usage: ps [ -aAdeflcjLPy ] [ -o format ] [ -t termlist ]
        [ -u userlist ] [ -U userlist ] [ -G grouplist ]
        [ -p proclist ] [ -g pgrplist ] [ -s sidlist ]
  'format' is one or more of:
        user ruser group rgroup uid ruid gid rgid pid ppid pgid sid taskid
        pri opri pcpu pmem vsz rss osz nice class time etime stime
        f s c lwp nlwp psr tty addr wchan fname comm args projid project
   rc=256
   test3.out not created