Timeline for How do I set $? or the return code in Bash?
Current License: CC BY-SA 4.0
9 events
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| Jan 29, 2020 at 13:33 | comment | added | boweeb |
@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).
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| Jul 3, 2019 at 5:30 | comment | added | toolforger |
@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.
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| Dec 6, 2018 at 18:35 | history | edited | Dennis Williamson | CC BY-SA 4.0 |
additional information
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| Mar 21, 2018 at 14:00 | comment | added | boweeb |
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.
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| May 23, 2017 at 12:32 | history | edited | URL Rewriter Bot |
replaced http://stackoverflow.com/ with https://stackoverflow.com/
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| Jul 7, 2016 at 15:50 | history | edited | Dennis Williamson | CC BY-SA 3.0 |
additional information
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| Jul 14, 2015 at 4:40 | comment | added | Dennis Williamson | @ElliotChance: The dollar sign in my answer represents the prompt and works as-is. What you propose would also work, but isn't necessary. | |
| Jul 14, 2015 at 4:35 | comment | added | Elliot Chance |
Should be $(exit 42); echo "$?"
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| May 5, 2012 at 0:58 | history | answered | Dennis Williamson | CC BY-SA 3.0 |