this post was submitted on 15 Jan 2025
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    My heart goes out to shell programmers who have to support posix sh (lemmy.world)
    submitted 1 day ago by [email protected] to c/[email protected]
    94 comments fedilink hide all child comments
     

    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.

    (page 2) 44 comments
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    [–] [email protected] 9 points 1 day ago (1 children)

    A lot of people call set -euo pipefail the "strict mode" for bash programming, as a reference to "use strict"; in JavaScript.

    In other words, always add this if you want to stay sane unless you're a shellcheck user.

    load more comments (1 replies)
    [–] [email protected] 5 points 1 day ago (2 children)

    I have written 5 shell scripts ever, and only 1 of them has been more complex than "I want to alias this single command"

    I can't imagine being an actual shell dev

    [–] [email protected] 4 points 1 day ago (1 children)

    only 1 of them has been more complex than “I want to alias this single command”

    I have some literal shell aliases that took me hours to debug...

    [–] [email protected] 1 points 1 day ago (1 children)

    I do not envy you.

    [–] [email protected] 3 points 1 day ago

    Nah, it's in the past.

    But people, if you are writing a command that detects a terminal to decide to color its output or not, please add some overriding parameters to it.

    [–] [email protected] 1 points 1 day ago

    It really isn't bad especially if you use ash

    [–] [email protected] -1 points 23 hours ago* (last edited 20 hours ago) (3 children)

    just use python instead.

    • wrap around subprocess.run(), to call to system utils
    • use pathlib.Path for file paths and reading/writing to files
    • use shutil.which() to resolve utilities from your Path env var

    Here's an example of some python i use to launch vscode (and terminals, but that requires dbus)

    
from pathlib import Path
from shutil import which
from subprocess import run

def _run(cmds: list[str], cwd=None):
    p = run(cmds, cwd=cwd)

    # raises an error if return code is non-zero
    p.check_returncode()

    return p

VSCODE = which('code')
SUDO   = which('sudo')
DOCKER = which('docker')

proj_dir = Path('/path/to/repo')

docker_compose = proj_dir / 'docker/'

windows = [
  proj_dir / 'code',
  proj_dir / 'more_code',
  proj_dir / 'even_more_code/subfolder',
]
for w in windows:
  _run([VSCODE, w])

_run([SUDO, DOCKER, 'compose', 'up', '-d'], cwd=docker_compose)
    load more comments (3 replies)
    [–] [email protected] -1 points 1 day ago (3 children)

    #!/usr/bin/python

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