misc/blkid.8.in

.\" 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 \-h
]
[
[
.B \-c
.I cachefile
]
.B \-s
.I savecachefile
]
[
.B \-p
]
[
.B \-t
.I token
]...
[
.B \-v
]
[
.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
.I <cachefile>
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 \-p
Probe all available devices.  This is the default when displaying
tokens.  When searching for a token normally the cache file is
used to locate the device and only that device is probed (to ensure
cache coherency) and all devices are probed only if the token cannot
be found in the cache.
.TP
.B \-s
.I tag
.I tag
is of the form
.I NAME
and the resulting token is shown for each (specified) device that has
such a tag.  It is possible to specify multiple
.I tag
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
.I token
.I token
is of the form
.IB NAME = value
and that specific token is searched for in the cache or among all visible
block devices and additionally any specified devices.  If that token is
not found, no output is shown.  Common values for
.I NAME
include
.BR TYPE ,
.BR LABEL ,
and
.BR UUID .
.TP
.B \-v
Display version number and exit.
.SH RETURN VALUE
The UUID of the form 1b4e28ba-2fa1-11d2-883f-b9a761bde3fb (in
.BR printf (3)
format "%08x-%04x-%04x-%04x-%012x") is output to the standard output.
.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 return 2.  For usage or other errors
return 4.
.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)