nbdkit-probing(1) NBDKIT nbdkit-probing(1) NAME nbdkit-probing - how to probe for nbdkit configuration and plugins SYNOPSIS nbdkit --version nbdkit --dump-config nbdkit --short-options nbdkit --long-options nbdkit PLUGIN --dump-plugin nbdkit PLUGIN --version nbdkit --filter=FILTER null --version nbdkit --filter=FILTER null --dump-plugin DESCRIPTION You can query information about nbdkit and available plugins and filters using the nbdkit binary. This can include whether nbdkit is installed, and whether plugins or filters are installed. Note: If you are looking for information about USDT probes, see nbd- kit-tracing(3). Query if nbdkit is installed Use this command to see if the nbdkit program is installed: nbdkit --version This will fail with an error and non-zero exit code if nbdkit is not in- stalled or not working. Query basic configuration nbdkit --dump-config lists information about how nbdkit was configured. The most important fields in the output are the name of the directory where nbdkit looks for plugins and the version of nbdkit, eg: plugindir=/usr/lib64/nbdkit/plugins version=1.20.1 version_major=1 version_minor=20 Test nbdkit ^a=Y version To test if nbdkit aY a particular version is installed, use the --dump-con- fig option and look for the "version_major" and "version_minor" fields: $ nbdkit --dump-config | grep ^version_minor version_minor=20 $ major=$( nbdkit --dump-config | grep ^version_major | cut -d= -f2 ) $ minor=$( nbdkit --dump-config | grep ^version_minor | cut -d= -f2 ) $ if [ $major -eq 1 ] && [ $minor -lt 12 ] then echo 'nbdkit >= 1.12 is required'; exit 1; fi These fields were first added in nbdkit 1.16.5 and were not present in ear- lier versions. You can also probe the minimum version using pkg-config(1). See "PKG-CON- FIG/PKGCONF" in nbdkit-plugin(3). Find out if nbdkit implements a command line option To test if a specific single letter option (like -D) or long option (like --name) is supported by nbdkit, use: nbdkit --short-options | grep -sq '^-D$' nbdkit --long-options | grep -sq '^--name$' Query information about a particular plugin nbdkit pluginname --dump-plugin (where pluginname is the name or full path of a plugin) will dump informa- tion about that plugin, eg: $ nbdkit file --dump-plugin path=/usr/lib64/nbdkit/plugins/nbdkit-file-plugin.so name=file version=1.20.1 api_version=1 struct_size=176 thread_model=serialize_requests [etc] Plugins which ship with nbdkit usually have the same version as the corre- sponding nbdkit binary. The nbdkit binary will always be able to utilize plugins compiled against an older version of the header; however, newer plugins may not be fully supported by an older nbdkit binary (for example, a plugin compiled with "NBDKIT_API_VERSION" of 2 fails to load with an older nbdkit that only knows "NBDKIT_API_VERSION" 1). Query information about a particular filter You can use the --dump-plugin option to dump information about a filter, by using the null plugin with the --filter parameter: $ nbdkit null --filter=qcow2dec --dump-plugin [...] qcow2dec_path=/usr/lib64/nbdkit/filters/nbdkit-qcow2dec-filter.so qcow2dec_name=qcow2dec qcow2dec_deflate=yes qcow2dec_zstd=yes Detect if a plugin is installed To find out if a plugin is installed (and working) in the plugin directory, use: $ nbdkit foo --version nbdkit: error: cannot open plugin 'foo': /usr/lib64/nbdkit/plugins/nbdkit-foo-plugin.so: cannot open shared object file: No such file or directory Use 'nbdkit --help' or read the nbdkit(1) manual page for documentation. This will fail with an error and non-zero exit code if the "foo" plugin cannot be loaded. Note it is better to test for the existence of plugins this way rather than just seeing if the .so file exists, because nbdkit will load the plugin and check that all its dependencies can be satisfied, and also that plugin reg- istration works. List all plugins in the plugin directory You could simply get the plugin directory (from --dump-config) and list all files in this directory called nbdkit-*-plugin.so. However a better test is to run --dump-plugin (see above) on each one to check that it is working and all of its dependencies are installed. A com- plete shell script which does this is: #!/bin/sh - plugindir=`nbdkit --dump-config | grep ^plugindir= | sed 's/[^=]*=//'` for f in $plugindir/nbdkit-*-plugin.so; do if nbdkit "$f" --version >/dev/null 2>&1; then b=`echo "$f" | sed 's,.*/nbdkit-\(.*\)-plugin.so$,\1,'` echo "$b ($f)" fi done Detect if a filter is installed To find out if a filter is installed (and working) use --version with the "null" plugin and the name of the filter to test: nbdkit --version --filter=foo null This will fail with an error and non-zero exit code if the "foo" filter cannot be loaded. SEE ALSO nbdkit(1). AUTHORS Eric Blake Richard W.M. Jones Pino Toscano COPYRIGHT Copyright Red Hat LICENSE Redistribution and use in source and binary forms, with or without modifi- cation, 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 no- tice, this list of conditions and the following disclaimer in the docu- mentation 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 EX- PRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DIS- CLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE LIABLE FOR ANY DI- RECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SER- VICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABIL- ITY, 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 DAM- AGE. nbdkit-1.46.2 2026-08-30 nbdkit-probing(1)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | AUTHORS | COPYRIGHT | LICENSE
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