Fish Shell 4 is written in Rust [LWN.net]

Fish Shell 4 is written in Rust

Posted Feb 12, 2025 23:05 UTC (Wed) by Nikratio (subscriber, #71966)
Parent article: Rewriting essential Linux packages in Rust

With regards to the question about rewriting a shell in Rust: the fish project is going that (https://fishshell.com/blog/rustport/)

to post comments

Fish Shell 4 is written in Rust

Posted Feb 13, 2025 23:17 UTC (Thu) by intgr (subscriber, #39733) [Link] (3 responses)

Fish is great as an interactive shell, but it's explicitly not POSIX compatible. It cannot run nontrivial shell scripts that work in most other shells. So not a replacement for /bin/sh.

Fish Shell 4 is written in Rust

Posted Feb 15, 2025 6:25 UTC (Sat) by marcH (subscriber, #57642) [Link] (2 responses)

Many quick and dirty scripts start from my command line history. Conversely, I often copy/paste and "import" functions or other code from scripts to my command line for interactively using and/or testing it. This sort of interactive back and forth is too convenient, productive and important and I really don't want to lose it. So, "fish" is out.

Is zsh "compatible enough" with POSIX? Does not have to be 100% for the above. If not, is there some other, fancy new shell that is significantly better than bash and that I should try? I'd like not to lose too much readline "compatibility" either. readline key strokes are close to universal so why should I learn new, different ones? Except for new features of course. It's painful enough to switch between readline and vi commands already.

Fish Shell 4 is written in Rust

Posted Feb 15, 2025 23:33 UTC (Sat) by intgr (subscriber, #39733) [Link]

> zsh "compatible enough" with POSIX?

My understanding is yes, zsh is a proper POSIX shell and even implements some bashisms.

Fish Shell 4 is written in Rust

Posted Feb 17, 2025 13:50 UTC (Mon) by taladar (subscriber, #68407) [Link]

zsh can run pretty much any POSIX command unaltered but there are definitely some of the more advanced features in zsh interactive use you couldn't just copy into a bash script without modification (a lot of the globbing stuff comes to mind).

There are also some subtleties that make it unwise to test if a command in a bash script behaves exactly as desired in zsh instead of bash, particularly around sub shells and undefined variables.