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.

  • renzev@lemmy.worldOPEnglish
    5·
    4 hours ago

    No, sorry. I’m a python dev and I love python, but there’s no way I’m using it for scripting. Trying to use python as a shell language just has you passing data across Popen calls with a sea of .decode and .encode. You’re doing the same stuff you would be doing in shell, but with a less concise syntax. Literally all of python’s benefits (classes, types, lists) are negated because all of the tools you’re using when writing scripts are processing raw text anyway. Not to mention the version incompatibility thing. You use an f-string in a spicy way once, and suddenly your “script” is incompatible with half of all python installations out there, which is made worse by the fact that almost every distro has a very narrow selection of python versions available on their package manager. With shell you have the least common denominator of posix sh. With Python, some distros rush ahead to the latest release, while other hang on to ancient versions. Even print("hello world") isn’t guaranteed to work, since some LTS ubuntu versions still have python pointing to python2.

    The quickest cure for thinking that Python “solves” the problems of shell is to first learn good practices of shell, and then trying to port an existing shell script to python. That’ll change your opinion quickly enough.