1nbdkit-probing(1)                   NBDKIT                   nbdkit-probing(1)
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NAME

6       nbdkit-probing - how to probe for nbdkit configuration and plugins
7

SYNOPSIS

9        nbdkit --dump-config
10
11        nbdkit PLUGIN --dump-plugin
12
13        nbdkit --version
14
15        nbdkit PLUGIN --version
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17        nbdkit --filter=FILTER null --version
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DESCRIPTION

20       You can query information about nbdkit and available plugins and
21       filters using the nbdkit binary.  This can include whether nbdkit is
22       installed, and whether plugins or filters and installed.
23
24   Query if nbdkit is installed
25       Use this command to see if the nbdkit program is installed:
26
27        nbdkit --version
28
29       This will fail with an error and non-zero exit code if the nbdkit is
30       not installed or not working.
31
32   Query basic configuration
33        nbdkit --dump-config
34
35       lists information about how nbdkit was configured.  The most important
36       fields in the output are the name of the directory where nbdkit looks
37       for plugins and the version of nbdkit, eg:
38
39        plugindir=/usr/lib64/nbdkit/plugins
40        version=1.2.3
41
42   Query information about a particular plugin
43        nbdkit pluginname --dump-plugin
44
45       (where pluginname is the name or full path of a plugin) will dump
46       information about that plugin, eg:
47
48        $ nbdkit file --dump-plugin
49        path=/usr/lib64/nbdkit/plugins/nbdkit-file-plugin.so
50        name=file
51        version=1.2.3
52        api_version=1
53        struct_size=176
54        thread_model=serialize_requests
55        [etc]
56
57       Plugins which ship with nbdkit usually have the same version as the
58       corresponding nbdkit binary.  The nbdkit binary will always be able to
59       utilize plugins compiled against an older version of the header;
60       however, newer plugins may not be fully supported by an older nbdkit
61       binary (for example, a plugin compiled with "NBDKIT_API_VERSION" of 2
62       fails to load with an older nbdkit that only knows "NBDKIT_API_VERSION"
63       1).
64
65   Detect if a plugin is installed
66       To find out if a plugin is installed (and working) in the plugin
67       directory, use:
68
69        $ nbdkit foo --version
70        nbdkit: error: cannot open plugin 'foo': /usr/lib64/nbdkit/plugins/nbdkit-foo-plugin.so: cannot open shared object file: No such file or directory
71        Use 'nbdkit --help' or read the nbdkit(1) manual page for documentation.
72
73       This will fail with an error and non-zero exit code if the "foo" plugin
74       cannot be loaded.
75
76       Note it is better to test for the existence of plugins this way rather
77       than just seeing if the .so file exists, because nbdkit will load the
78       plugin and check that all its dependencies can be satisfied, and also
79       that plugin registration works.
80
81   List all plugins in the plugin directory
82       You could simply get the plugin directory (from --dump-config) and list
83       all files in this directory called nbdkit-*-plugin.so.
84
85       However a better test is to run --dump-plugin (see above) on each one
86       to check that it is working and all of its dependencies are installed.
87       A complete shell script which does this is:
88
89        #!/bin/sh -
90        plugindir=`nbdkit --dump-config | grep ^plugindir= | sed 's/[^=]*=//'`
91        for f in $plugindir/nbdkit-*-plugin.so; do
92            if nbdkit "$f" --version >/dev/null 2>&1; then
93                b=`echo "$f" | sed 's,.*/nbdkit-\(.*\)-plugin.so$,\1,'`
94                echo "$b ($f)"
95            fi
96        done
97
98   Detect if a filter is installed
99       To find out if a filter is installed (and working) use --version with
100       the "null" plugin and the name of the filter to test:
101
102        nbdkit --version --filter=foo null
103
104       This will fail with an error and non-zero exit code if the "foo" filter
105       cannot be loaded.
106

SEE ALSO

108       nbdkit(1).
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AUTHORS

111       Eric Blake
112
113       Richard W.M. Jones
114
115       Pino Toscano
116

118       Copyright (C) 2013-2020 Red Hat Inc.
119

LICENSE

121       Redistribution and use in source and binary forms, with or without
122       modification, are permitted provided that the following conditions are
123       met:
124
125       ·   Redistributions of source code must retain the above copyright
126           notice, this list of conditions and the following disclaimer.
127
128       ·   Redistributions in binary form must reproduce the above copyright
129           notice, this list of conditions and the following disclaimer in the
130           documentation and/or other materials provided with the
131           distribution.
132
133       ·   Neither the name of Red Hat nor the names of its contributors may
134           be used to endorse or promote products derived from this software
135           without specific prior written permission.
136
137       THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND ANY
138       EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
139       IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
140       PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR CONTRIBUTORS BE
141       LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
142       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
143       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
144       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
145       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
146       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
147       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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151nbdkit-1.18.4                     2020-04-16                 nbdkit-probing(1)
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