How do you shell expand your variables and why?

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• thingsiplay@kbin.social ⁨1⁩ ⁨year⁩ ago

  @zephyr echo "${HOME}/docs"

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  • bloopernova@programming.dev ⁨1⁩ ⁨year⁩ ago

    This is the best way. It’s also the way the Shellcheck wants them.

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    • thingsiplay@kbin.social ⁨1⁩ ⁨year⁩ ago

      @bloopernova As you mention it, here the links for anyone interested: Online tool https://www.shellcheck.net/ and you can install it locally too https://github.com/koalaman/shellcheck .

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    • gamma@programming.dev ⁨1⁩ ⁨year⁩ ago

      Shellcheck doesn’t insist on braces unless it thinks you need them.

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  • brennesel@feddit.de ⁨1⁩ ⁨year⁩ ago

    This is the right way

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  • drew_belloc@programming.dev ⁨1⁩ ⁨year⁩ ago

    This is the way

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  • Simulation6@sopuli.xyz ⁨1⁩ ⁨year⁩ ago

    I also do this so the variables are more easily spotted.

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  • gamma@programming.dev ⁨1⁩ ⁨year⁩ ago

    This has never stuck with me, and I hadn’t thought about why until now. I have two reasons why I will always write ${x}_$y.z instead of ${x}_${y}.z:

    • Syntax highlighting and shellcheck have always caught the cases I need to add braces to prevent $x_ being expanded as ${x_}.
    • I write a lot of Zsh. In Zsh, braces are optional in way more cases. “$#array[3]” actually prints the length of the third item in array, rather than (Bash:) the number of positional parameters, then the string ‘array[3]’.

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• ilega_dh@feddit.nl ⁨1⁩ ⁨year⁩ ago

  find “$(echo $HOME > variable_holder.txt && cat variable_holder.txt)/$(cat alphabet.txt | grep “d”) $(cat alphabet.txt | grep “o”)$(cat alphabet.txt | grep “c”)$(cat alphabet.txt | grep “s”)”

  This is the easiest method

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  • igorlogius@lemmy.world ⁨1⁩ ⁨year⁩ ago

    no eval ?

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  • ale@lemmy.world ⁨1⁩ ⁨year⁩ ago

    This really enterprises my bash.

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  • thingsiplay@kbin.social ⁨1⁩ ⁨year⁩ ago

    @ilega_dh You don't need cat in cases when grep "d" alphabet.txt can read from file too.

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    • gendulf@kbin.social ⁨1⁩ ⁨year⁩ ago

      To be safe, should probably output grep to a file, then cat that.

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  • eager_eagle@lemmy.world ⁨1⁩ ⁨year⁩ ago

    when you’re paid by character written

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  • monsterpiece42@reddthat.com ⁨1⁩ ⁨year⁩ ago

    What should I search to better understand what is written here? Don’t mind learning myself, just looking for the correct keywords. Thanks!

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    • oneiros@lemmy.blahaj.zone ⁨1⁩ ⁨year⁩ ago

      This comment is a joke and you wouldn’t want to do it like that in reality, but here are some related keywords you could look up: “Unix cat”, “Unix pipeline”, “grep”, “output redirection”, “command substitution”.

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    • priapus@sh.itjust.works ⁨1⁩ ⁨year⁩ ago

      ExplainShell should help

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    • marcos@lemmy.world ⁨1⁩ ⁨year⁩ ago

      Read the Bash manual. That one patter on the GP is called “Command Substitution”, you can search for it.

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• key@lemmy.keychat.org ⁨1⁩ ⁨year⁩ ago

  First one, then the other, then I forget the quotes, then I put them in single quotes by accident, then I utilize that “default value” colon syntax in case I’m missing HOME , then I just stick to ~ for the rest of the file.

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• karlhungus@lemmy.ca ⁨1⁩ ⁨year⁩ ago

  I do what the linter tells me to: github.com/koalaman/shellcheck

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• gamma@programming.dev ⁨1⁩ ⁨year⁩ ago

  Typically find “$HOME/docs”, but with a few caveats:

  • In Zsh or Fish, the quotes are unnecessary: find $HOME/docs

  • If I’m using anything potentially destructive: mv “${HOME:?}/bin” …

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• thingsiplay@kbin.social ⁨1⁩ ⁨year⁩ ago

  @zephyr echo "${HOME}"

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