$ perl -le 'for (0..3) { system( "Idonotexist $_" ) }'
$ perl -le 'for (0..3) { system( "Idonotexist $_" ) == 0 or warn "system problem (exit $?): $!\n" }'
system problem (exit -1): No such file or directory
system problem (exit -1): No such file or directory
system problem (exit -1): No such file or directory
system problem (exit -1): No such file or directory
$