Best way to run external app only if it exists

Question

I've got a Perl script that as one of its final steps creates a compressed version of a file it has created. Due to some unfortunate setups, we cannot guarantee that a given customer will have a specific compression function. I want to put something like this together:

if ($has_jar) {
    system("jar -c $compressed_file $infile");
}
elsif ($has_zip) {
    system("zip -j $compressed_file $infile");
}
else {
    copy($infile, $compressed_file);
}

Where if they don't have either of the compression apps, it will just copy the file into the location of the compressed file without compressing it.

My sticky wicket here is that I'm not quite sure what the best way is to determine if they have jar or zip. It looks like I can used exec() instead of system() and take advantage of the fact that it only returns if it fails, but the script actually does do a couple of things after this, so that wouldn't work.

I also need this to be a portable solution as this script runs on both Windows and various Unix distros. Thanks in advance.

Answer 1

I think your best bet is File::Which.

Answer 2

See my multi-which.