nbd_aio_connect_command(3)

📦
version 1.25.8 · 18 versions
, in centos-stream 10

💅 nbd_aio_connect_command(3) — a libnbd moment

okay bestie, so this is a page from LIBNBD (that's the libnbd manual, section 3, iykyk) and it's about nbd_aio_connect_command. Fair warning: the "aio" stands for asynchronous, and the "connect" is very much doing what it says on the tin. Let's get into it 🦋

✨ NAME ✨

nbd_aio_connect_command — connect to the NBD server. That's the whole vibe. That's the assignment. 🎯

🌸 SYNOPSIS 🌸

#include <libnbd.h>

int nbd_aio_connect_command (
      struct nbd_handle *h, char **argv
    );

That's it. That's the whole function signature. No cap. 🫶

🎀 DESCRIPTION 🎀

So here's the tea ☕: this function runs the command as a subprocess, and then it begins connecting to it over stdin/stdout. Like, it literally spawns your command and then chats with it through its standard input and standard output. Iconic behavior, honestly.

And the parameters? They behave exactly as documented in nbd_connect_command(3). So if you're confused about argv and what it wants, that's the page to go read. This page is just the async-flavored version of that one. 💫

💖 RETURN VALUE 💖

If the call is successful, the function returns 0. Slay. ✨

😭 ERRORS 😭

On error, -1 is returned. Not slay. 💀

For how to get further details of the error, refer to "ERROR HANDLING" in libnbd(3) — that's where the actual error lore lives.

Also, important vibe check: the following parameters must not be NULL: "h", "argv". For more information see "Non-NULL parameters" in libnbd(3). Do not pass NULL, bestie, I'm begging 🙏

🧚 NOTES 🧚

⭐ Asynchronous connect call ⭐

So because this is the async version, the connection attempt doesn't just finish instantly — you can check if the connection attempt is still underway by calling nbd_aio_is_connecting(3). That's your "are we there yet" function. 🚗

Now here's where it gets a little nuanced, so pay attention:

Two different finish lines, depending on whether opt_mode is on. Main character energy for both paths. 👑

🔥 HANDLE STATE 🔥

nbd_aio_connect_command can be called when the handle is in the following state:

  • Handle created, before connecting — ✅ allowed (this is the one, this is the moment)
  • Connecting — ❌ error
  • Connecting & handshaking (opt_mode) — ❌ error
  • Connected to the server — ❌ error
  • Connection shut down — ❌ error
  • Handle dead — ❌ error

So basically: call it before you connect, and only before you connect. One window. One shot. Don't come back later trying again, it's giving error 💀

🌈 VERSION 🌈

This function first appeared in libnbd 1.0. It's an OG. 💅

If you need to test if this function is available at compile time, check if the following macro is defined:

#define LIBNBD_HAVE_NBD_AIO_CONNECT_COMMAND 1

That macro is your little "yes it exists" badge. Wear it proudly 🎖️

🦋 SEE ALSO 🦋

Go read these, they're all part of the same friend group:

💜 AUTHORS 💜

  • Eric Blake
  • Richard W.M. Jones

Legends, both of them. Respect the architects 🫡

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

fr fr, read the license — it's the whole reason you get to use this for free 💖

and that's the page, bestie!! 🌸 written against libnbd-1.25.8, dated 2026-10-13, page nbd_aio_connect_command(3) — go forth and connect asynchronously, you absolute icon 🧚‍♀️✨

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