awesome/the-art-of-command-line
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Merge pull request #574 from wyattscarpenter/patch-1

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copy-editing around mention of pipefail
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Joshua Levy 2018-10-03 14:29:19 -07:00 committed by GitHub
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@ -125,7 +125,7 @@ Notes:
- Understand that care is needed when variables and filenames include whitespace. Surround your Bash variables with quotes, e.g. `"$FOO"`. Prefer the `-0` or `-print0` options to enable null characters to delimit filenames, e.g. `locate -0 pattern | xargs -0 ls -al` or `find / -print0 -type d | xargs -0 ls -al`. To iterate on filenames containing whitespace in a for loop, set your IFS to be a newline only using `IFS=$'\n'`. - Understand that care is needed when variables and filenames include whitespace. Surround your Bash variables with quotes, e.g. `"$FOO"`. Prefer the `-0` or `-print0` options to enable null characters to delimit filenames, e.g. `locate -0 pattern | xargs -0 ls -al` or `find / -print0 -type d | xargs -0 ls -al`. To iterate on filenames containing whitespace in a for loop, set your IFS to be a newline only using `IFS=$'\n'`.
- In Bash scripts, use `set -x` (or the variant `set -v`, which logs raw input, including unexpanded variables and comments) for debugging output. Use strict modes unless you have a good reason not to: Use `set -e` to abort on errors (nonzero exit code). Use `set -u` to detect unset variable usages. Consider `set -o pipefail` too, to on errors within pipes, too (though read up on it more if you do, as this topic is a bit subtle). For more involved scripts, also use `trap` on EXIT or ERR. A useful habit is to start a script like this, which will make it detect and abort on common errors and print a message: - In Bash scripts, use `set -x` (or the variant `set -v`, which logs raw input, including unexpanded variables and comments) for debugging output. Use strict modes unless you have a good reason not to: Use `set -e` to abort on errors (nonzero exit code). Use `set -u` to detect unset variable usages. Consider `set -o pipefail` too, to abort on errors within pipes (though read up on it more if you do, as this topic is a bit subtle). For more involved scripts, also use `trap` on EXIT or ERR. A useful habit is to start a script like this, which will make it detect and abort on common errors and print a message:
```bash ```bash
set -euo pipefail set -euo pipefail
trap "echo 'error: Script failed: see failed command above'" ERR trap "echo 'error: Script failed: see failed command above'" ERR