My heart goes out to shell programmers who have to support posix sh
My heart goes out to shell programmers who have to support posix sh
Explanation for newbies:
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Shell is the programming language that you use when you open a terminal on linux or mac os. Well, actually "shell" is a family of languages with many different implementations (bash, dash, ash, zsh, ksh, fish, ....)
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Writing programs in shell (called "shell scripts") is a harrowing experience because the language is optimized for interactive use at a terminal, not writing extensive applications
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The two lines in the meme change the shell's behavior to be slightly less headache-inducing for the programmer:
set -euo pipefailis the short form of the following three commands:set -e: exit on the first command that fails, rather than plowing through ignoring all errorsset -u: treat references to undefined variables as errorsset -o pipefail: If a command piped into another command fails, treat that as an error
export LC_ALL=Ctells other programs to not do weird things depending on locale. For example, it forcesseqto output numbers with a period as the decimal separator, even on systems where coma is the default decimal separator (russian, dutch, etc.).
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The title text references "posix", which is a document that standardizes, among other things, what features a shell must have. Posix does not require a shell to implement
pipefail, so if you want your script to run on as many different platforms as possible, then you cannot use that feature.
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Shell is great, but if you're using it as a programming language then you're going to have a bad time. It's great for scripting, but if you find yourself actually programming in it then save yourself the headache and use an actual language!
Your scientists were so preoccupied with whether they could, they didn’t stop to think if they should
Honestly, the fact that bash exposes low level networking primitives like a TCP socket via /dev/TCP is such a godsend. I've written an HTTP client in Bash before when I needed to get some data off of a box that had a fucked up filesystem and only had an emergency shell. I would have been totally fucked without /dev/tcp, so I'm glad things like it exist.
EDIT: oh, the article author is just using netcat, not doing it all in pure bash. That's a more practical choice, although it's way less fun and cursed.
EDIT: here's a webserver written entirely in bash. No netcat, just the /bin/bash binary https://github.com/dzove855/Bash-web-server
Alpine linux, one of the most popular distros to use inside docker containers (and arguably good for desktop, servers, and embedded) is held together by shell scripts, and it's doing just fine. The installer, helper commands, and init scripts are all written for busybox sh. But I guess that falls under "scripting" by your definition.
Aka busybox in disguise 🥸
The few times I've used shell for programming it was in strict work environments where anything compiled was not allowed without a ton of red tape.
Wouldn't something interpreted like python be a better solution?
For more complicated input/output file handling, certainly.
Little shell scripts do great though if all you need to do is concatenate files by piping them.
It's like the Internet, it's not one big truck but a series of tubes.
Yep, in my mind piping together other commands is scripting not programming, exactly what shell scripts are for!
With enough regex and sed/awk you might be able to make even complicated stuff work. I'm not a regex guru (but I do occasionally dabble in the dark arts).
I feel attacked. https://github.com/fmstrat/gam
