Choosing the first available program from list of options

GNU tar accepts an external program to perform compression, via the option --use-compress-program. I'd normally want pigz if it's available, but if not, fallback to gzip. Is there a compact way to get represent this? Yes!

which --skip-alias --skip-functions pigz gzip 2>/dev/null | head -1

GNU which accepts multiple arguments, printing out the resolution for each as they're found or an error if not. GNU which also allows finding only full-fledged binaries, not aliases or functions. This is exactly what we want: list the paths to these programs, in the order I gave, then pluck the first one.

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