Shell Scripting

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From Ash, Bash and Csh to Xonsh, Ysh and Zsh; all shell languages are welcome here!

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If you find a solution to your problem by other means, please take your time to write down the steps you used to solve your problem in the original post. You can potentially help others having the same problem!
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Keep posts about shell scripting! Here are some guidelines to help:

Allowed: Release Announcement of a command-line program designed for scripted use (e.g. bash, bats, awk, jq, coreutils/moreutils)
Allowed: Tutorials on using shell languages or supplementary tools designed for scripted use
Allowed: Code review/help requests for shell languages or supplementary tools designed for scripted use
NOT Allowed: Announcement of a CLI or TUI program that is not designed for scripted use (Yes, your fancy Zsh plugin which pretty-prints the date and time using only builtins is very cool, but unless you actually want to discuss the code itself, please check out !commandline instead!)
NOT Allowed: Domain-specific tutorials that do not involve shell scripting as a core component (e.g. docker-compose, ansible, nix). If you really love one of these, I'm sure there's a community out there ready to talk about them!
NOT Allowed: Code review requests for non-shell programming languages and configuration languages (e.g. Python, Yaml)

In general, if your submission text is primarily shell code, then it is welcome here!

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What are the most inscrutable lines of $SHELL you've ever written? (programming.dev)

submitted 1 year ago* (last edited 1 year ago) by [email protected] to c/[email protected]

48 comments fedilink hide all child comments

I'm sure some of you have absolute monstrosities of sigils (I know I do, in my .zshrc alone). Post them without context, and try and guess what other users's lines are. If you want to provide context or guess, use the markdown editor to spoiler-tag your guesses and explanations!

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[–] [email protected] 3 points 1 year ago* (last edited 1 year ago) (1 children)

It's not bash itself that was the complex part exactly, but I have a CI/CD pipeline that generates epub files from markdown. In some cases I have custom designed covers, but where a cover doesn't exist I have a bash script generate one using Imagemagick.

I wanted to generate the cover in one command to lessen performance impacts and disk I/O, but it took me a few weeks to figure out how to do it all in a single Imagemagick command:

convert \
    -size 960x1536 \
    -background "${backgroundColor}" \
    -fill "${textColor}" \
    -font "Liberation-Serif" \
    -pointsize 96 \
    -gravity north \
    caption:"${title}" \
    -bordercolor "rgb(0, 0, 0)" \
    -border 2 \
    -bordercolor "${borderColor}" \
    -border 40 \
    -background none \
    -fill "${textColor}" \
    -font "Liberation-Serif" \
    -pointsize 48 \
    -gravity south \
    -geometry +0-800 \
    -annotate +0+40 "${author}" \
    "${destination}cover.jpg"

Eventually it made an abstract sense to me, and I was able to bring it down to two commands and then finally one. This generates a cover with a selected background color (based on content type) and contains title text that will wrap to an inner border.

I think I had to give up on the author being wrapped, but it's much smaller than the title anyway.

[–] [email protected] 2 points 1 year ago (1 children)

Nice work! I've definitely had some fun with convert recently, as you might tell from the community banner.

spoiler

It is an image showing the script I used to create it 😛.

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago) (1 children)

That's certainly a script! 😅

[–] [email protected] 2 points 1 year ago* (last edited 1 year ago) (1 children)

It's a little more complex than needed, for the pixelated background I used xcolor names and then modulated them darker, but then relented and used hexcodes for the text in the foreground.

[–] [email protected] 1 points 1 year ago

It's very impressive! I try to write legible code first, and if my shell scripts get too complex, I move on to another tool typically:

C# scripting
Python
PowerShell
Node.js

That might be why I don't have many cryptic examples.