I am writing POSIX shell scripts quite often, mostly for speed and portability. Though, that might not even be needed, as bash might have gotten a speed increase compared to dash, ash and whatnot.
Here are some tests I plan to run to see if the speed difference is still the case
As my normal user shell I use fish since quite some time. I enjoy
- a simple PS1 that shows the git branch, git status, truncated path where I am
- autocompletion based on history
- autosuggestions from
-h or --help even if the tool has no autocompletions in other shells
abbr instead or alias is quite cool to not forget the actual commands. But I can live without
I dont use more features really. I have a couple of fish functions, and fish might just be a better bash with easier syntax. But bash is the standard, so I never use them anyways.
I wouldnt want to switch to zsh because it is weird permissively licensed. But if it is faster or better than bash, maybe?
I also like that fish is completely rewritten in rust. There is rusty-bash aka. sushi shell, anyone use that? Is is compatible with modules?
Are these extensions just scripts that you run on startup of the shell?
I have
fishset as the default command to run when my terminal emulator starts, but my system-wide default shell isbashand I always throw a#!/bin/shor#!/bin/bashshebang at the top of my scripts either way.With that setup, I hardly notice
fish's syntax differences. Are you using it like that, too?Scripting in fish is so wonderful though.
Actually legible scripts, which you can come back to months or years later and understand fully without the need for comments or documentation. Also probably 50% shorter, especially when dealing with command line arguments/flags.
I think so. If I do
./script.shI get fish errors, same with. script.shOnly
sh script.shworks, which is dash inside of fishThat is definitely not right. That sounds like you don't have a shebang or it isn't defined correctly. The shebang has to be the very first thing in the script, with no whitespace before it. It gets read out by the kernel, which very dumbly checks the first few bytes.
And well, such a shebang should also work for Python or the like. If you copy the first script in this link into a file
script.py, then runchmod +x script.pyand finally run./script.py, does that printHello, World!?Well my shebang is #!/bin/sh which might break because I am on NixOS XD
So fish might fallback to using fish
The most compatible shebang, that will also work on nixOS, is
#!/usr/bin/env bash(and you can replace bash with whatever interpreter likeshofpython3). It'll also respect environment overrides and allI'm on NixOS for my personal laptop, too. I just tried it and well,
#!/bin/bashapparently does not work, but#!/bin/shdoes.The file
/bin/shdoes also exist as a symlink for me:Does that point into the
bashpackage for you, too?Edit: And for
#!/bin/bash, the output was:I think i use dash as my standard shell, but fish as my user shell. So it might point to fish, which doesnt work. Only using fish in my terminal could fix this.