Cause `less` to exit with a non-zero status code?

Question

I would like to have the following command structure:

command && check-status | less && followup-command

This would pause the execution while the user interacted with less. How can the user force less to exit with a non-zero status to prevent followup-command from running?

I am currently using less 458 (POSIX regular expressions)

score 15 · Accepted Answer · edited Oct 09 '16 at 11:58

15

In the simple case, you can ask less not to handle SIGINT, then Control-C will kill it and the exit code will be non-zero. Do this with option -K.

command && check-status | less -K && followup-command

As a workaround for older versions of less, you can do something like

command && bash -c 'trap "exit 1" int;check-status | less -K;' && followup-command

If you don't have -K, omit it, but you'll have to signal and then type quit too.

edited Oct 09 '16 at 11:58

Jeff Schaller

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answered Jun 05 '16 at 16:36

meuh

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`less -K` still returns a 0 exit code on ctrl-c for me. v418 on mac and v436 on linux. `less -K test; echo $? => 0` – Matt Jun 06 '16 at 04:21
that's sad. it's ok on a v458 and v481 for me.The man page for `-K` explicitly says *exit ...(with status 2)*. Does yours? – meuh Jun 06 '16 at 05:01
man only says `Causes less to exit immediately` > http://www.greenwoodsoftware.com/less/news.443.html – Matt Jun 06 '16 at 07:06
I've added a workaround for an older less. – meuh Jun 06 '16 at 07:31
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Note that the `^C` will also kill `check-status` if it's not finished already. – Stéphane Chazelas Jun 06 '16 at 08:35
Terminating `check-status` is an acceptable and preferred result of killing `less`, in my use case. – user2943160 Jun 17 '16 at 03:27

Cause `less` to exit with a non-zero status code?

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