nbd_get_subprocess_pid(3)

📦
version 1.25.8 · 14 versions
, in centos-stream 10

💅 nbd_get_subprocess_pid(3) — from the libnbd manual, section 3, bestie

okay so you opened the libnbd man pages, iconic of you honestly. welcome to nbd_get_subprocess_pid, a little function that tells you the PID of the subprocess libnbd spawned for you. it's giving "who even is that child process" energy and we're obsessed 🎀

✨ NAME ✨

nbd_get_subprocess_pid — get the process ID of the subprocess 🫶

🌸 SYNOPSIS 🌸

#include <libnbd.h>

int64_t nbd_get_subprocess_pid (
          struct nbd_handle *h
        );

🦋 DESCRIPTION 🦋

so like, for connections that actually spin up a subprocess — think nbd_connect_command(3) and friends — this function hands you back the process ID (PID) of that subprocess. literally just the PID. that's the whole vibe 💖

heads up bestie: this is only supported on some platforms. no cap. if you're on a platform that doesn't do it, that's just how it is 😭

and what's it for? mainly debugging cases. like, the classic use: you wanna learn where to attach gdb(1) so you can diagnose a crash happening inside the NBD server subprocess. that's it, that's the main character use case 🔥

⭐ RETURN VALUE ⭐

this call returns a 64 bit signed integer ≥ 0. so a big ol' non-negative number, i.e. your PID 💜

💀 ERRORS 💀

on error, -1 is returned. yeah. minus one. the saddest number 🙈

for how to get further details of the error, refer to "ERROR HANDLING" in libnbd(3).

also, these parameters must not be NULL: "h". for more info, see "Non-NULL parameters" in libnbd(3). don't pass NULL, like, ever, please and thank you 🫶

🌈 VERSION 🌈

this function first appeared in libnbd 1.22.

wanna check at compile time if it's available? just see if this macro is defined:

#define LIBNBD_HAVE_NBD_GET_SUBPROCESS_PID 1

slay, conditional compilation ✨

👑 SEE ALSO 👑

go read them, iykyk 📚

🧚 AUTHORS 🧚

  • Eric Blake
  • Richard W.M. Jones

kings of the codebase, honestly 👑

Copyright Red Hat

💅 LICENSE 💅

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

and that's the whole page bestie 🎀 this was nbd_get_subprocess_pid(3) from libnbd-1.25.8, dated 2026-10-13 — go forth and attach your debugger, periodt 💖✨

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