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.\" Copyright 2000 Andreas Dilger (adilger@turbolinux.com)
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.\" This man page was created for blkid from e2fsprogs-1.25.
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.\" This file may be copied under the terms of the GNU Public License.
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.\" Based on uuidgen, Mon Sep 17 10:42:12 2000, Andreas Dilger
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.TH BLKID 8 "February 2009" "Linux" "MAINTENANCE COMMANDS"
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blkid \- command\-line utility to locate/print block device attributes
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program is the command-line interface to working with
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library. It can determine the type of content (e.g. filesystem, swap)
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a block device holds, and also attributes (tokens, NAME=value pairs)
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from the content metadata (e.g. LABEL or UUID fields).
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has two main forms of operation: either searching for a device with a
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specific NAME=value pair, or displaying NAME=value pairs for one or
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instead of reading from the default cache file
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If you want to start with a clean cache (i.e. don't report devices previously
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scanned but not necessarily available at this time), specify
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Perform a garbage collection pass on the blkid cache to remove
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devices which no longer exist.
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Display a usage message and exit.
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Look up one device that matches the search parameter specified using
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option. If there are multiple devices that match the specified search
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parameter, then the device with the highest priority is returned, and/or
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the first device found at a given priority. Device types in order of
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decreasing priority are Device Mapper, EVMS, LVM, MD, and finally regular
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block devices. If this option is not specified,
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will print all of the devices that match the search parameter.
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Look up one device that uses the label (same as: -l -o device -t
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LABEL=<label>). This look up method is able to reliable use /dev/disk/by-label
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udev symlinks (depends on setting in /etc/blkid.conf). Avoid to use the
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symlinks directly. It is not reliable to use the symlinks without verification.
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The \fB-L\fR option is portable and works on systems with and without udev.
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Restrict probing functions to defined (comma separated) list of "usage" types.
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Supported usage types are: filesystem, raid, crypto and other. The list can be
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prefixed with "no" to specify the usage types which should be ignored. For example:
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blkid -p -u filesystem,other /dev/sda1
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probes for all filesystems and others (e.g. swap) formats, and
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blkid -p -u noraid /dev/sda1
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probes for all supported formats exclude RAIDs. This option is useful with
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Look up one device that uses the uuid. For more details see the \fB-L\fR option.
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output using the specified format. The
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print all tags (the default)
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print the value of the tags
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print the devices in a user-friendly format
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print the device name only
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vol_id compatible mode; usable in udev rules
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Probe at the given offset (only useful with \fB-p\fR).
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Switch to low-level probing mode (bypass cache)"
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For each (specified) device, show only the tags that match
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It is possible to specify multiple
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options. If no tag is specified, then all tokens are shown for all
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In order to just refresh the cache without showing any tokens, use
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with no other options.
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Overwrite device/file size (only useful with \fB-p\fR).
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.BI \-t " NAME" = "value"
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Search for block devices with tokens named
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and display any devices which are found.
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If there are no devices specified on the command line, all block devices
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will be searched; otherwise only the specified devices are searched.
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Display version number and exit.
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.BI \-w " writecachefile"
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Write the device cache to
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instead of writing it to the default cache file
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If you don't want to save the cache to the default file, specify
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If not specified it will be the same file as that given by the
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Display tokens from only the specified device. It is possible to
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options on the command line. If none is given, all devices which
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are shown, if they are recognized.
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If the specified token was found, or if any tags were shown from (specified)
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devices, 0 is returned. If the specified token was not found, or no
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(specified) devices could be identified, an exit code of 2 is returned.
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For usage or other errors, an exit code of 4 is returned.
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was written by Andreas Dilger for libblkid and improved by Theodore Ts'o
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The blkid command is part of the util-linux-ng package and is available from
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ftp://ftp.kernel.org/pub/linux/utils/util-linux-ng/.