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Like programming in bash (lemmy.ml)
submitted 2 years ago by to c/programmer_humor@programming.dev
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[–] 61 points 2 years ago (2 children)

PSA: Run ShellCheck on your shell scripts. It turns up a shocking number of programming errors. https://www.shellcheck.net/

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  • [–] 8 points 2 years ago

    Thank you for this. About a year ago I came across ShellCheck thanks to a comment just like this on Reddit. I also happened to be getting towards the end of a project which included hundreds of lines of shell scripts across dozens of files.

    It turns out that despite my workplace having done quite a bit of shell scripting for previous projects, no one had heard about Shell Check. We had been using similar analysis tools for other languages but nothing for shell scripts. As you say, it turned up a huge number of errors, including some pretty spicy ones when we first started using it. It was genuinely surprising to see how many unique and terrible ways the scripts could have failed.

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  • [–] 6 points 2 years ago (2 children)

    I wish it had a more comprehensive auto correct feature. I maintain a huge bash repository and have tried to use it, and it common makes mistakes. None of us maintainers have time to rewrite the scripts to match standards.

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  • [–] 7 points 2 years ago (1 child)

    I honestly think autocorrecting your scripts would do more harm than good. ShellCheck tells you about potential issues, but It's up to you to determine the correct behavior.

    For example, how could it know whether cat $foo should be cat "$foo", or whether the script actually relies on word splitting? It's possible that $foo intentionally contains multiple paths.

    Maybe there are autofixable errors I'm not thinking of.

    FYI, it's possible to gradually adopt ShellCheck by setting --severity=error and working your way down to warnings and so on. Alternatively, you can add one-off #shellcheck ignore SC1234 comments before offending lines to silence warnings.

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  • [–] 4 points 2 years ago

    For example, how could it know whether cat $foo should be cat "$foo", or whether the script actually relies on word splitting? It's possible that $foo intentionally contains multiple paths.

    Last time I used ShellCheck (yesterday funnily enough) I had written ports+=($(get_elixir_ports)) to split the input since get_elixir_ports returns a string of space separated ports. It worked exactly as intended, but ShellCheck still recommended to make the splitting explicit rather than implicit.

    The ShellCheck docs recommended

    IFS=" " read -r -a elixir_ports <<< "(get_elixir_ports)"
ports+=("${elixir_ports[@]}")
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  • [–] 3 points 2 years ago

    Then you’ll have to find the time later when this leads to bugs. If you write against bash while declaring it POSIX shell, but then a random system’s sh doesn’t implement a certain thing, you’ll be SOL. Or what exactly do you mean by “match standards”?

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