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nbdkit-readonly-filter - Man Page

switch a plugin between read-only and writable

Synopsis

 nbdkit --filter=readonly PLUGIN

 nbdkit --filter=readonly PLUGIN readonly-file=/tmp/ro

Description

nbdkit-readonly-filter is an nbdkit filter that has two modes:

Trying to write to the filter when the filter is enforcing read-only mode will cause EPERM ("Operation not permitted") to be returned to the client.

nbdkit-protect-filter(1) is a related filter which can write-protect parts of a plugin (eg only the boot sector). nbdkit-error-filter(1) is another filter which can be used for the same purpose as this filter but is more complicated to use.  See also the -r option described in the nbdkit(1) manual.

Example

Make a disk read-only 60 seconds after nbdkit is started:

 rm -f /tmp/ro
 nbdkit --filter=readonly file disk.img readonly-file=/tmp/ro
 sleep 60; touch /tmp/ro

Parameters

readonly-file=PATHNAME

If this parameter is used, the filter makes the underlying plugin read-only when PATHNAME exists, otherwise the plugin is writable as usual.

If this parameter is not used, the filter always makes the underlying plugin read-only.

Files

$filterdir/nbdkit-readonly-filter.so

The filter.

Use nbdkit --dump-config to find the location of $filterdir.

Version

nbdkit-readonly-filter first appeared in nbdkit 1.38.

See Also

nbdkit(1), nbdkit-error-filter(1), nbdkit-file-plugin(1), nbdkit-full-plugin(1), nbdkit-protect-filter(1), nbdkit-filter(3).

Authors

Richard W.M. Jones

License

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

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.

Referenced By

nbdkit(1), nbdkit-error-filter(1), nbdkit-file-plugin(1), nbdkit-filter(3), nbdkit-full-plugin(1), nbdkit-protect-filter(1), nbdkit-release-notes-1.38(1), nbdkit-rotational-filter(1).

2024-06-12 nbdkit-1.39.7