Proc::...::Unix(3pm)

✨ Proc::...::Unix(3pm) ✨

okay bestie, welcome to the Proc::...::Unix(3pm) page 💖 this is the Unix-flavored corner of the Proc::Background universe, and honestly? it's giving backstage pass energy. let's get into it.

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🌸 NAME 🌸

Proc::Background::Unix — the Unix-specific implementation of process create/wait/kill 🫶

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💅 DESCRIPTION 💅

bestie. listen. this module does not have a public interface. like, none. zero. nada. 🙈

use Proc::Background instead. that's the main character. this one is the stagehand. periodt.

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🎀 IMPLEMENTATION 🎀

🍓 Command vs. Exec 🍓

okay so here's the lore 🌈 Unix systems start a new process by creating a mirror of the current process (fork) and then having it alter its own state to prepare for the new program, and then calling exec to replace the running code with code loaded from a new file. iconic behavior tbh.

but wait — there's a second common method, where the user wants to specify a command line string as they would type it in their shell. in that case, the actual program being executed is the shell, and the command line is given as one element of its argument list. the way that works is lowkey genius ngl.

Perl already supports both methods 💜 so like: if you pass one string to exec containing shell characters, it calls the shell, and if you pass multiple arguments, it directly invokes exec.

this module mostly just lets Perl's exec do its job — let it cook, fr fr — but it also checks for the existence of the executable first, so that errors are easier to catch 🎀 and that check is skipped if there is a single-string command line. noted.

Unix lets you run a different executable than what is listed in the first argument 👑 (this feature lets one Unix executable behave as multiple different programs depending on what name it sees in the first argument — like one actor playing the whole cast, ate). you can use that feature by passing separate options of exe and command to this module's constructor instead of a simple argument list. but — and this is important bestie — you can't mix an exe option with a shell-interpreted command line string. no mixing. the vibe check says no. 🚫

⭐ Errors during Exec ⭐

if the autodie option is enabled, and the system supports FD_CLOEXEC, this module uses a trick where the forked child relays any errors through a pipe so that the parent can throw and handle the exception directly instead of creating a child process that is dead-on-arrival with the error on STDERR 💀

like. instead of the child just showing up already deceased with the error on STDERR, the parent actually gets to handle it. slay.

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💖 AUTHORS 💖

• Blair Zajac <blair@orcaware.com> ✨
• Michael Conrad <mike@nrdvana.net> ✨

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🦋 VERSION 🦋

version 1.32 🎀

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👑 COPYRIGHT AND LICENSE 👑

This software is copyright (c) 2023 by Michael Conrad, (C) 1998-2009 by Blair Zajac.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself. 🌸

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and that's the whole page, bestie 🫶 no cap. this was perl v5.38.2, dated 2024-03-07, and yes we made it all the way through Proc::...::Unix(3pm) together 💜 you ate that. now go use Proc::Background like I told you 😭✨