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  • Should be $(exit 42); echo "$?"
    – Elliot Chance
    Commented Jul 14, 2015 at 4:35
  • 3
    @ElliotChance: The dollar sign in my answer represents the prompt and works as-is. What you propose would also work, but isn't necessary.
    – Dennis Williamson
    Commented Jul 14, 2015 at 4:40
  • Note that you can use the range 0-255 but what actually happens is a modulo against 256. That means you can exit 300 and $? will be 44. Also, exit -1 would return 255 (a strange habit I've seen a lot). Just something to be aware of. It's best to just return the value you desire so stick to 0-255 so you (or someone else) won't get surprised.
    – boweeb
    Commented Mar 21, 2018 at 14:00
  • @boweeb -1 mod X == X-1 is pretty normal, you essentially continue the 0,1,...,X-1 sequence into negatives. See en.wikipedia.org/wiki/Modulo_operation for variations and rationale.
    – toolforger
    Commented Jul 3, 2019 at 5:30
  • @toolforger -- yup... that's what I said above. I'm not confused about the math. I'm confused why a developer would want to use a convoluted way to get to 255. My best guess is the convention implies the 255 return code isn't meant to be meaningful (and writing it as -1 is marginally easier to write(?)). RC 1 is common for a generic/unspecified error but I've never seen anything actually eval $? for 255 (specifically).
    – boweeb
    Commented Jan 29, 2020 at 13:33