Ask HN: What's the best obscure but useful CLI tool?

Re:Ask HN: What's the best obscure but useful CLI tool? by john-tells-all on Wednesday April 05, 2023 @11:58AM (#35456280)

entr -- when a file changes, run a command

I use this on literally 100% of my projects. Normally it's "when my source changes, run tests" or sometimes "when files change, do 'terraform plan' to see what would change".

Using this one command shortens developer feedback loops from a minute to microseconds! And you don't have to think about it! It's magic.

`ls -1 *.py | entr pytest`

`git ls-files | entr terraform plan`

For more, see our friend and national treasure Julia Evans: https://jvns.ca/blog/2020/06/28/entr/

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Re:Ask HN: What's the best obscure but useful CLI tool? by lordleft on Wednesday April 05, 2023 @01:46PM (#35457852)

That is incredible, I had no idea this existed -- thanks for sharing!

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Re:Ask HN: What's the best obscure but useful CLI tool? by qup on Wednesday April 05, 2023 @04:35PM (#35460007)

20+ years of linux, didn't know about it. Will be daily-driving it now, thanks for chiming in.

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Re:Ask HN: What's the best obscure but useful CLI tool? by rthomas6 on Wednesday April 05, 2023 @04:54PM (#35460235)

That's awesome. Seems like it would pair well with Make.

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Re:Ask HN: What's the best obscure but useful CLI tool? by coreyp_1 on Wednesday April 05, 2023 @06:10PM (#35461091)

I use inotifywait with make for a similar effect. I save a source file and my code is re-compiled and tests are run.

I love it!

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Re:Ask HN: What's the best obscure but useful CLI tool? by john-tells-all on Wednesday April 12, 2023 @12:31AM (#35535024)

absolutely. 100% of my projects use Entr ("run thing on file change"), and Make ("use short name to run a complex script, e.g. test -> pytest").

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