5 ms·

For an actually intentional, non-cursed version of this, see the nix-shell shebang [0]: > #! /usr/bin/env nix-shell > #! nix-shell -i python3 -p python3P

For an actually intentional, non-cursed version of this, see the nix-shell shebang [0]: > #! /usr/bin/env nix-shell > #! nix-shell -i python3 -p python3Packages.pillow python3Packages.ansicolor > > # scale image by 50% > import sys, PIL.Image, ansicolor > path = sys.argv[1] > image = PIL.Image.open(path) > factor = 0.5 > image = image.resize((round(image.width * factor), round(image.height * factor))) > path = path + ".s50.jpg" > image.save(path) > print(ansicolor.green(f"done {path}")) Just `chmod +x` and you have an executable with all dependencies you specify! [0] https://nixos.wiki/wiki/Nix-shell_shebang https://nixos.wiki/wiki/Nix-shell_shebang

miduil 3y ago
Totally, some practical use of that here as well: https://dpc.pw/posts/nix-users-you-can-start-using-rust-scripts-already/ https://dpc.pw/posts/nix-users-you-can-start-using-rust-scri...
d0mine 3y ago
There are pip-run, pipx run, etc for Python-specific use-cases.
nmz 3y ago
There's a 256byte limit for #! so this shouldn't work at all. EDIT: Now I see its badly formatted, Either way, be careful with #! size limits.
- pronoiac 3y ago
  Ah. I think two leading spaces fix this? I'll try: #! /usr/bin/env nix-shell #! nix-shell -i python3 -p python3Packages.pillow python3Packages.ansicolor # scale image by 50% import sys, PIL.Image, ansicolor path = sys.argv[1] image = PIL.Image.open(path) factor = 0.5 image = image.resize((round(image.width \* factor), round(image.height \* factor))) path = path + ".s50.jpg" image.save(path) print(ansicolor.green(f"done {path}"))
zopa 3y ago
I use nix-shell, and mostly I love it. But it’s important to be aware that the above means “Go get the latest(*) versions of python, pillow and ansicolor and run this code in an environment where they’re available.” It doesn’t do any version-pinning of your dependencies. That might be what you want, but maybe not: it’s frustrating when a script that worked yesterday won’t work today, or will only work after some big download. My own rule of thumb is that nix-shell is great for quick one-offs and for sharing environments. For local tools and anything else I’m sharing with my future self, it’s usually better to write a nix expression and install it, which gives me access to Nix’s (excellent) rollback system, and lets me upgrade on my schedule, not upstream’s. * - ‘Latest’ according to whatever Nix channel checkout currently applies. Which you can change, of course, but the point is it’s external to the script.
- YoshiRulz 3y ago
  You can "pin" Nixpkgs with this style of invocation as well, see https://nixos.wiki/wiki/Nix-shell_shebang#Pinning_nixpkgs https://nixos.wiki/wiki/Nix-shell_shebang#Pinning_nixpkgs. But I agree that if you're writing a shell script (or small Python/Ruby scripts) that you'll be running often, it's better to package it (e.g. with writeShellScriptBin) and install to profile.
jdxcode 3y ago
I documented how to do it with mise-en-place: https://mise.jdx.dev/tips-and-tricks.html#shebang https://mise.jdx.dev/tips-and-tricks.html#shebang
adastra22 3y ago
I'm pretty sure TFA is “intentional” too. Isn't this the whole point of shebang?
tomberek 3y ago
I'm a huge fan of the Nix shebang, and we now have a variant of it for the new CLI. Feedback on it would be appreciated.

miduil 3y ago

Totally, some practical use of that here as well: https://dpc.pw/posts/nix-users-you-can-start-using-rust-scripts-already/ https://dpc.pw/posts/nix-users-you-can-start-using-rust-scri...

d0mine 3y ago

There are pip-run, pipx run, etc for Python-specific use-cases.

nmz 3y ago

There's a 256byte limit for #! so this shouldn't work at all. EDIT: Now I see its badly formatted, Either way, be careful with #! size limits.

pronoiac 3y ago
Ah. I think two leading spaces fix this? I'll try: #! /usr/bin/env nix-shell #! nix-shell -i python3 -p python3Packages.pillow python3Packages.ansicolor # scale image by 50% import sys, PIL.Image, ansicolor path = sys.argv[1] image = PIL.Image.open(path) factor = 0.5 image = image.resize((round(image.width \* factor), round(image.height \* factor))) path = path + ".s50.jpg" image.save(path) print(ansicolor.green(f"done {path}"))

zopa 3y ago

I use nix-shell, and mostly I love it. But it’s important to be aware that the above means “Go get the latest(*) versions of python, pillow and ansicolor and run this code in an environment where they’re available.” It doesn’t do any version-pinning of your dependencies. That might be what you want, but maybe not: it’s frustrating when a script that worked yesterday won’t work today, or will only work after some big download. My own rule of thumb is that nix-shell is great for quick one-offs and for sharing environments. For local tools and anything else I’m sharing with my future self, it’s usually better to write a nix expression and install it, which gives me access to Nix’s (excellent) rollback system, and lets me upgrade on my schedule, not upstream’s. * - ‘Latest’ according to whatever Nix channel checkout currently applies. Which you can change, of course, but the point is it’s external to the script.

YoshiRulz 3y ago
You can "pin" Nixpkgs with this style of invocation as well, see https://nixos.wiki/wiki/Nix-shell_shebang#Pinning_nixpkgs https://nixos.wiki/wiki/Nix-shell_shebang#Pinning_nixpkgs. But I agree that if you're writing a shell script (or small Python/Ruby scripts) that you'll be running often, it's better to package it (e.g. with writeShellScriptBin) and install to profile.

jdxcode 3y ago

I documented how to do it with mise-en-place: https://mise.jdx.dev/tips-and-tricks.html#shebang https://mise.jdx.dev/tips-and-tricks.html#shebang

adastra22 3y ago

I'm pretty sure TFA is “intentional” too. Isn't this the whole point of shebang?

tomberek 3y ago

I'm a huge fan of the Nix shebang, and we now have a variant of it for the new CLI. Feedback on it would be appreciated.