nbdkit-openonce-filter(1)

📦
version 1.48.1 · 8 versions
, in fedora 44

✨ nbdkit-openonce-filter ✨

okay bestie, so this is a page from the NBDKIT manual, and today we're doing nbdkit-openonce-filter(1). yes that's the whole name. it's long. she's iconic. let's go 💅

🌸 NAME 🌸

nbdkit-openonce-filter — open the underlying plugin once. that's it. that's the whole vibe. one (1) open. no cap 🫶

🦋 SYNOPSIS 🦋

nbdkit --filter=openonce PLUGIN

👑 DESCRIPTION 👑

so nbdkit-openonce-filter is a filter for nbdkit(1) and what it does is — you guessed it — open the underlying plugin once. per export. literally one time. 💖

when is this the move? when your plugin is slow to open/connect, like nbdkit-ssh-plugin(1) or nbdkit-vddk-plugin(1). those girlies take forever to wake up, and you're not about to sit there waiting every single time. so you open once and keep it. main character energy. ✨

but ok, we have to be real, because i love you and i would never lie to you. there are some disadvantages:

  • Multiple NBD clients may be sharing one connection to the plugin, which might cause performance issues. 😭 like, everybody crammed into one lil connection. it's giving group project.
  • The plugin stays open until nbdkit shuts down. she does not leave. she lives there now. 🙈
  • This defeats multi-conn. if nbdkit advertises multi-conn, NBD clients may make multiple connections but will end up connecting to the same underlying plugin instance. so you think you're getting parallel connections but bestie you are not. (also go look at nbdkit-multi-conn-filter(1) if that's the energy you actually want.)

🎀 PARAMETERS 🎀

There are no parameters specific to nbdkit-openonce-filter.

none. zero. zilch. nothing bespoke for this filter, periodt.

any parameters you do pass get passed through to and processed by the underlying plugin in the normal way. so whatever the plugin wants, the plugin gets. 🫶

🍓 FILES 🍓

  • $filterdir/nbdkit-openonce-filter.so — the filter itself, the actual girlboss file. 💖
    • use nbdkit --dump-config to find the location of $filterdir. yes, literally run that. iykyk. ✨

⭐ VERSION ⭐

nbdkit-openonce-filter first appeared in nbdkit 1.44. baby girl is relatively new, be nice to her 🌸

🌈 SEE ALSO 🌈

the whole squad, go read them, they're all slaying in their own way:

💜 AUTHORS 💜

Richard W.M. Jones — thank you king, we owe you everything 🫶

Copyright Red Hat

💀 LICENSE 💀

ok so here's the legal bit, and i'm not gonna water it down because this is the part where you actually have to pay attention, bestie. redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  • Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 📋
  • Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 📋
  • Neither the name of Red Hat nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. 🚫
THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

like, it's AS IS. all caps. i don't make the rules, i just relay them dramatically. 😭

and that's the page!! mwah 💋 this one came from nbdkit-1.48.1, dated 2026-08-29 — so if you're reading this from the future, hi, hope the filter's still slaying. bye bestie, go open something exactly once 💖✨🎀🦋

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