BLKID(8)

NAME
blkid - command-line utility to locate/print block device attributes

SYNOPSIS
blkid [ -hlv ] [ [ -c cachefile ] -w writecachefile ] [ -o format ] [ -s tag ] [ -t NAME=value ] [ device ... ]

DESCRIPTION
The blkid program is the command-line interface to working with libuuid(3) library. It can determine the type of content (e.g. filesystem, swap) a block device holds, and also attributes (tokens, NAME=value pairs) from the content metadata (e.g. LABEL or UUID fields).

blkid has two main forms of operation: either searching for a device with a specific NAME=value pair, or displaying NAME=value pairs for one or more devices.

OPTIONS

-c  Read from cachefile instead of reading from the default cache file /etc/blkid.tab. If you want to start with a clean cache (i.e. don't report devices previously scanned but not necessarily available at this time), specify /dev/null.

-h  Display a usage message and exit.

-l  Look up the device that matches the search parameter specified using the -t option, assuming that there is only one matching the search parameter. For a system with a large number of disks, this will be more efficient by avoiding the need to revalidate devices unless absolutely necessary. If this option is not specified, blkid will use a less efficient approach, which allows blkid to print all of the devices that match the search parameter.

    This option is best used for tag searches such as LABEL=data_vol or UUID=e280469a-d06f-4c0b-b068-44f3b576029e. If you want blkid to print all of the ext3 filesystems using a search parameter such as TYPE=ext3, then this option should not be used.

-o  Display blkid's output using the specified format. The format parameter may be full, (the default), value, (only print the value of any tags printed by blkid) or device (only print the device name).

-s  Show only the tags for each (specified) device that match tag. It is possible to specify multiple -s options. If no tag is specified, then all tokens are shown for all (specified) devices. In order to just refresh the cache without showing any tokens use -s none with no other options.

-t  Search for block devices with tokens named NAME that have the value value, and display any devices which are found. Common values for NAME include TYPE, LABEL, and UUID. If there are no devices specified on the command line, all block devices will be searched; otherwise, only search the devices specified by the user.

-v  Display version number and exit.

-w  <writecachefile> Write the device cache to writecachefile instead of writing it to the default cache file /etc/blkid.tab. If you don't want to save the cache to the default file, specify /dev/null. If not specified it will be the same file as that given by the -c option.

<device>
    Display tokens from only the specified device. It is possible to give multiple <device> options on the command line. If none is given, all devices which appear in /proc/partitions are shown, if they are recognized.

RETURN CODE
If the specified token was found, or if any tags were shown from (specified) devices 0 is returned. If the specified token was not found, or no (specified) devices could be identified, an exit code of 2 is returned. For usage or other errors, an exit code of 4 is returned.

AUTHOR
blkid was written by Andreas Dilger for libblkid.

AVAILABILITY
blkid is part the e2fsprogs package since version 1.26 and is available from http://e2fsprogs.sourceforge.net.

SEE ALSO
libblkid(3)