NAME

       nbdkit-probing - how to probe for nbdkit configuration and plugins

SYNOPSIS

        nbdkit --dump-config

        nbdkit PLUGIN --dump-plugin

        nbdkit --version

        nbdkit PLUGIN --version

        nbdkit --filter=FILTER null --version

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 and installed.

   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 the nbdkit is not installed 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=1.2.3

   Query information about a particular plugin
        nbdkit pluginname --dump-plugin

       (where pluginname is the name or full path of a plugin) will dump information about that plugin, eg:

        $ nbdkit file --dump-plugin
        path=/usr/lib64/nbdkit/plugins/nbdkit-file-plugin.so
        name=file
        version=1.2.3
        api_version=1
        struct_size=176
        thread_model=serialize_requests
        [etc]

       Plugins which ship with nbdkit usually have the same version as the corresponding 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).

   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 registration 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 complete 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 (C) 2013-2020 Red Hat Inc.

LICENSE

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