package Shell::DWIM;
use warnings;
use strict;

our ($RUN_ERROR, $OS_ERR);
*OS_ERROR = $^O =~ m{VMS|MSWin|OS/2} ? \$^E : \$!;

sub sysdwim {
    local $@;
    my $retval = eval { system @_ };
    
    if ($retval == 0) {
        $RUN_ERROR = undef;
        return 1;
    }

    $RUN_ERROR =
        $? > 0   ? $?        :  # non-zero exit code from program
        $? == -1 ? "$OS_ERR" :  # couldn't launch program for some reason
        $@       ? $@        :  # eval failed
                 "system() failed with unknown error";

    return;
}

sub import {
    my $pkg = (caller)[0];
    *{$pkg . ($_[0] eq 'override' ? "::system" : "::sysdwim")} = \&sysdwim;
    *{$pkg . "::RUN_ERROR"} = \$RUN_ERROR;
}

1;