sub try_shell {
    my $shell = shift;
print "line 1\n";
    my $out = eval { capture($shell, '-c', 'echo good') };
print "line 2\n";
    if ($out and $out =~ /^good$/) {
print "line 3\n";
        if ($shell =~ /ksh/) {
print "line 4\n";
            if (defined (my $version = eval { `$shell --version 2>&1` })) {
print "line 5\n";
                if ($version =~ /version\s+sh\s+\(AT\&T\s+Research\)/) {
                    diag "skipping tests for broken AT&T ksh shell!";
                    return undef;
                }
            }
        }
print "line 6\n";
        if ($shell eq '!!fish') {
            diag "TODO: add support for fish shell!";
            return undef;
        }
        return 1;
    }
    return undef;
}