Explanation for newbies:

  • 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, …)

  • 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

  • The two lines in the meme change the shell’s behavior to be slightly less headache-inducing for the programmer:

    • set -euo pipefail is the short form of the following three commands:
      • set -e: exit on the first command that fails, rather than plowing through ignoring all errors
      • set -u: treat references to undefined variables as errors
      • set -o pipefail: If a command piped into another command fails, treat that as an error
    • export LC_ALL=C tells other programs to not do weird things depending on locale. For example, it forces seq to output numbers with a period as the decimal separator, even on systems where coma is the default decimal separator (russian, dutch, etc.).

  • 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.

    • smeg@feddit.ukEnglish
      14·
      11 hours ago

      Your scientists were so preoccupied with whether they could, they didn’t stop to think if they should

      • Badabinski@kbin.earth
        7·
        10 hours ago

        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