5

In the statement in the title, there is a problem that even if the statement is true, it will still exit with status 1 because, as I understand it:

[[ statement ]] || echo problem found ; exit 1

Evaluates to if the statement is false, echo problem found. Exit with status 1. Even if the statement evaluates true, the exit 1 still happens because it is separate. I thought to fix this by running it in a subshell like so:

[[ statement ]] || (echo problem found ; exit 1)

This seems to do what I want, but is it an acceptable way to handle this?

3 Answers 3

7

You must use

[[ statement ]] || { echo problem found ; exit 1; }

The difference is that the brace syntax doesn't create a subshell, which means the exit 1 applies to the current shell. If you use (exit 1) the subshell exits but the current shell continues running.

3

You need to use syntax like this :

[[ statement ]] || { echo problem found ; exit 1; }

and more accurate send standard error

[[ statement ]] || { echo >&2 "problem found"; exit 1; }
1
  • 1
    Thanks! More notes for beginners: 1) You must leave one whitespace after both the opening and closing brace. 2) Don't forget the semicolon after the last statement! If you do, you will get a very pointless (and misleading) error message: ''unexpected end of file'' (?!?) Feb 12, 2015 at 19:51
3

Don't try to be clever. Remember that debugging is twice as hard as writing, so when you're writing a program, be only half as clever as you can be.

if ! [[ statement ]]; then
  echo problem found
  exit 1
fi
1
  • +1 For the quote. I don't know why one-liners are so popular on SE and in general, as most of them are buggy and hard to understand/read.
    – user13742
    Dec 10, 2013 at 23:50

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