.\" Copyright 2000 Andreas Dilger (adilger@turbolinux.com)
.\"
.\" This man page was created for blkid from e2fsprogs-1.25.
.\" 
.\" This file may be copied under the terms of the GNU Public License.
.\" 
.\" Based on uuidgen, Mon Sep 17 10:42:12 2000, Andreas Dilger
.TH BLKID 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@"
.SH NAME
blkid \- command\-line utility to locate/print block device attributes
.SH SYNOPSIS
.B blkid 
[
.B \-hv
]
[
[
.B \-c
.I cachefile
]
.B \-w
.I writecachefile
]
[
.B \-o
.I format
]
[
.B \-s
.I tag
]
[
.B \-t
.IR NAME = value
]
[
.I device ...
]
.SH DESCRIPTION
The
.B blkid
program is the command-line interface to working with
.BR 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).
.PP
.B 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.
.SH OPTIONS
.TP
.B \-c
Read from
.I cachefile
instead of reading from the default cache file
.IR /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
.IR /dev/null.
.TP
.B \-h
Display a usage message and exit.
.TP
.B \-o 
Display 
.BR blkid 's
output using the specified format.  The
.I format
parameter may be 
.IR full ,
(the default), 
.IR  value ,
(only print the value of any tags printed by 
.BR blkid)
or 
.I device
(only print the device name).
.TP
.B \-s
Show only the tags for each (specified) device that match
.IR tag .
It is possible to specify multiple
.B \-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
.B "-s none"
with no other options.
.TP
.B \-t
Search for block devices with tokens named
.I NAME
that have the value 
.IR value ,
and display any devices which are found.
Common values for
.I NAME
include
.BR TYPE ,
.BR LABEL ,
and
.BR 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.
.TP
.B \-v
Display version number and exit.
.TP
.B \-w
.I <writecachefile>
Write the device cache to
.I writecachefile
instead of writing it to the default cache file
.IR /etc/blkid.tab .
If you don't want to save the cache to the default file, specify
.IR /dev/null.
If not specified it will be the same file as that given by the
.B -c
option.
.TP
.I <device>
Display tokens from only the specified device.  It is possible to
give multiple
.I <device>
options on the command line.  If none is given, all devices which
appear in
.I /proc/partitions
are shown, if they are recognized.
.SH "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.
.SH AUTHOR
.B blkid
was written by Andreas Dilger for libblkid.
.SH AVAILABILITY
.B blkid
is part the e2fsprogs package since version 1.26 and is available from
http://e2fsprogs.sourceforge.net.
.SH "SEE ALSO"
.BR libblkid (3)