diff options
Diffstat (limited to 'misc-utils/blkid.8')
| -rw-r--r-- | misc-utils/blkid.8 | 332 |
1 files changed, 332 insertions, 0 deletions
diff --git a/misc-utils/blkid.8 b/misc-utils/blkid.8 new file mode 100644 index 0000000..13b5edb --- /dev/null +++ b/misc-utils/blkid.8 @@ -0,0 +1,332 @@ +.\" Copyright 2000 Andreas Dilger (adilger@turbolinux.com) +.\" +.\" This file may be copied under the terms of the GNU Public License. +.TH BLKID 8 "March 2013" "util-linux" "System Administration" +.SH NAME +blkid \- locate/print block device attributes +.SH SYNOPSIS +.IP \fBblkid\fR +.BI \-\-label " label" +| +.BI \-\-uuid " uuid" + +.IP \fBblkid\fR +.RB [ \-\-no\-encoding +.B \-\-garbage\-collect \-\-list\-one \-\-cache\-file +.IR file ] +.RB [ \-\-output +.IR format ] +.RB [ \-\-match\-tag +.IR tag ] +.RB [ \-\-match\-token +.IR NAME=value ] +.RI [ device " ...]" + +.IP \fBblkid\fR +.BR \-\-probe " [" \-\-offset +.IR offset ] +.RB [ \-\-output +.IR format ] +.RB [ \-\-size +.IR size ] +.RB [ \-\-match\-tag +.IR tag ] +.RB [ \-\-match\-types +.IR list ] +.RB [ \-\-usages +.IR list ] +.IR device " ..." + +.IP \fBblkid\fR +.BR \-\-info " [" \-\-output +.IR format ] +.RB [ \-\-match\-tag +.IR tag ] +.IR device " ..." + +.SH DESCRIPTION +The +.B blkid +program is the command-line interface to working with the +.BR libblkid (3) +library. It can determine the type of content (e.g. filesystem or swap) +that a block device holds, and also the attributes (tokens, NAME=value pairs) +from the content metadata (e.g. LABEL or UUID fields). +.PP +.B It is recommended to use +.BR lsblk (8) +.B command to get information about block devices, or lsblk --fs to get an overview of filesystems, or +.BR findmnt (8) +.B to search in already mounted filesystems. +.PP +.RS +.BR lsblk (8) +provides more information, better control on output formatting, easy to use in +scripts and it does not require root permissions to get actual information. +.B blkid +reads information directly from devices and for non-root users +it returns cached unverified information. +.B blkid +is mostly designed for system services and to test libblkid functionality. +.RE + +.PP +When +.I device +is specified, tokens from only this device are displayed. +It is possible to specify multiple +.I device +arguments on the command line. +If none is given, all devices which appear in +.I /proc/partitions +are shown, if they are recognized. +.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 specified devices. + +For security reasons +.B blkid +silently ignores all devices where the probing result is ambivalent (multiple +colliding filesystems are detected). The low-level probing mode (\fB-p\fR) +provides more information and extra return code in this case. +It's recommended to use +.BR wipefs (8) +to get a detailed overview and to erase obsolete stuff (magic strings) from the device. + +.SH OPTIONS +The \fIsize\fR and \fIoffset\fR arguments may be followed by the multiplicative +suffixes like KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB +(the "iB" is optional, e.g. "K" has the same meaning as "KiB"), or the suffixes +KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB. +.TP +\fB\-c\fR, \fB\-\-cache\-file\fR \fIcachefile\fR +Read from +.I cachefile +instead of reading from the default cache file (see the CONFIGURATION FILE section +for more details). 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 +\fB\-d\fR, \fB\-\-no\-encoding\fR +Don't encode non-printing characters. The non-printing characters are encoded +by ^ and M- notation by default. Note that the \fB\-\-output udev\fR output format uses +a different encoding which cannot be disabled. +.TP +\fB\-g\fR, \fB\-\-garbage\-collect\fR +Perform a garbage collection pass on the blkid cache to remove +devices which no longer exist. +.TP +\fB\-h\fR, \fB\-\-help\fR +Display a usage message and exit. +.TP +\fB\-i\fR, \fB\-\-info\fR +Display information about I/O Limits (aka I/O topology). The 'export' output format is +automatically enabled. This option can be used together with the \fB\-\-probe\fR option. +.TP +\fB\-k\fR, \fB\-\-list\-filesystems\fR +List all known filesystems and RAIDs and exit. +.TP +\fB\-l\fR, \fB\-\-list\-one\fR +Look up only one device that matches the search parameter specified with the \fB\-\-match\-token\fR +option. If there are multiple devices that match the specified search +parameter, then the device with the highest priority is returned, and/or +the first device found at a given priority. Device types in order of +decreasing priority are: Device Mapper, EVMS, LVM, MD, and finally regular +block devices. If this option is not specified, +.B blkid +will print all of the devices that match the search parameter. +.TP +\fB\-L\fR, \fB\-\-label\fR \fIlabel\fR +Look up the device that uses this filesystem \fIlabel\fR; this is equal to +.BR "--list-one --output device --match-token LABEL=\fIlabel\fR" . +This lookup method is able to reliably use /dev/disk/by-label +udev symlinks (dependent on a setting in /etc/blkid.conf). Avoid using the +symlinks directly; it is not reliable to use the symlinks without verification. +The \fB-\-label\fR option works on systems with and without udev. + +Unfortunately, the original +.BR blkid (8) +from e2fsprogs uses the \fB-L\fR option as a +synonym for \fB-o list\fR. For better portability, use \fB-l -o device +-t LABEL=\fIlabel\fR and \fB-o list\fR in your scripts rather than the \fB-L\fR option. +.TP +\fB\-n\fR, \fB\-\-match\-types\fR \fIlist\fR +Restrict the probing functions to the specified (comma-separated) \fIlist\fR of +superblock types (names). +The list items may be prefixed with "no" to specify the types which should be ignored. +For example: +.sp + blkid --probe --match-types vfat,ext3,ext4 /dev/sda1 +.sp +probes for vfat, ext3 and ext4 filesystems, and +.sp + blkid --probe --match-types nominix /dev/sda1 +.sp +probes for all supported formats except minix filesystems. +This option is only useful together with \fB\-\-probe\fR. +.TP +\fB\-o\fR, \fB\-\-output\fR \fIformat\fR +Use the specified output format. Note that the order of variables and +devices is not fixed. See also option \fB-s\fR. The +.I format +parameter may be: +.RS +.TP +.B full +print all tags (the default) +.TP +.B value +print the value of the tags +.TP +.B list +print the devices in a user-friendly format; this output format is unsupported +for low-level probing (\fB\-\-probe\fR or \fB\-\-info\fR). + +This output format is \fBDEPRECATED\fR in favour of the +.BR lsblk (8) +command. +.TP +.B device +print the device name only; this output format is always enabled for the \fB\-\-label\fR +and \fB\-\-uuid\fR options +.TP +.B udev +print key="value" pairs for easy import into the udev environment; the keys are +prefixed by ID_FS_ or ID_PART_ prefixes. The value may be modified to be +safe for udev environment; allowed is plain ASCII, hex-escaping and valid UTF-8, +everything else (including whitespaces) is replaced with '_'. The keys with +_ENC postfix use hex-escaping for unsafe chars. + +The udev output returns the ID_FS_AMBIVALENT tag if more superblocks are detected, +and ID_PART_ENTRY_* tags are always returned for all partitions including empty +partitions. + +This output format is \fBDEPRECATED\fR. +.TP +.B export +print key=value pairs for easy import into the environment; this output format +is automatically enabled when I/O Limits (\fB\-\-info\fR option) are requested. + +The non-printing characters are encoded by ^ and M- notation and all +potentially unsafe characters are escaped. +.RE +.TP +\fB\-O\fR, \fB\-\-offset\fR \fIoffset\fR +Probe at the given \fIoffset\fR (only useful with \fB\-\-probe\fR). This option can be +used together with the \fB\-\-info\fR option. +.TP +\fB\-p\fR, \fB\-\-probe\fR +Switch to low-level superblock probing mode (bypassing the cache). + +Note that low-level probing also returns information about partition table type +(PTTYPE tag) and partitions (PART_ENTRY_* tags). The tag names produced by +low-level probing are based on names used internally by libblkid and it may be +different than when executed without \fB\-\-probe\fR (for example PART_ENTRY_UUID= vs +PARTUUID=). +.TP +\fB\-s\fR, \fB\-\-match\-tag\fR \fItag\fR +For each (specified) device, show only the tags that match +.IR tag . +It is possible to specify multiple +.B \-\-match\-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 "\-\-match\-tag none" +with no other options. +.TP +\fB\-S\fR, \fB\-\-size\fR \fIsize\fR +Override the size of device/file (only useful with \fB\-\-probe\fR). +.TP +\fB\-t\fR, \fB\-\-match\-token\fR \fINAME=value\fR +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 the specified devices are searched. +.TP +\fB\-u\fR, \fB\-\-usages\fR \fIlist\fR +Restrict the probing functions to the specified (comma-separated) \fIlist\fR of "usage" types. +Supported usage types are: filesystem, raid, crypto and other. The list items may be +prefixed with "no" to specify the usage types which should be ignored. For example: +.sp + blkid --probe --usages filesystem,other /dev/sda1 +.sp +probes for all filesystem and other (e.g. swap) formats, and +.sp + blkid --probe --usages noraid /dev/sda1 +.sp +probes for all supported formats except RAIDs. +This option is only useful together with \fB\-\-probe\fR. +.TP +\fB\-U\fR, \fB\-\-uuid\fR \fIuuid\fR +Look up the device that uses this filesystem \fIuuid\fR. For more details see the +\fB\-\-label\fR option. +.TP +\fB\-V\fR, \fB\-\-version\fR +Display version number and exit. +.SH "RETURN CODE" +If the specified device or device addressed by specified token (option +\fB\-\-match\-token\fR) was found and it's possible to gather any information about the +device, an exit code 0 is returned. Note the option \fB\-\-match\-tag\fR filters output +tags, but it does not affect return code. + +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. + +If an ambivalent probing result was detected by low-level probing mode (\fB\-p\fR), an exit code of 8 is +returned. +.SH CONFIGURATION FILE +The standard location of the +.I /etc/blkid.conf +config file can be overridden by the environment variable BLKID_CONF. +The following options control the libblkid library: +.TP +.I SEND_UEVENT=<yes|not> +Sends uevent when +.I /dev/disk/by-{label,uuid,partuuid,partlabel}/ +symlink does not match with LABEL, UUID, PARTUUID or PARTLABEL on the device. Default is "yes". +.TP +.I CACHE_FILE=<path> +Overrides the standard location of the cache file. This setting can be +overridden by the environment variable BLKID_FILE. Default is +.IR /run/blkid/blkid.tab , +or +.I /etc/blkid.tab +on systems without a /run directory. +.TP +.I EVALUATE=<methods> +Defines LABEL and UUID evaluation method(s). Currently, the libblkid library +supports the "udev" and "scan" methods. More than one method may be specified in +a comma-separated list. Default is "udev,scan". The "udev" method uses udev +.I /dev/disk/by-* +symlinks and the "scan" method scans all block devices from the +.I /proc/partitions +file. +.SH AUTHOR +.B blkid +was written by Andreas Dilger for libblkid and improved by Theodore Ts'o +and Karel Zak. +.SH ENVIRONMENT +.IP "Setting LIBBLKID_DEBUG=all enables debug output." +.SH SEE ALSO +.BR libblkid (3), +.BR findfs (8), +.BR lsblk (8), +.BR wipefs (8) +.SH AVAILABILITY +The blkid command is part of the util-linux package and is available from +https://www.kernel.org/pub/linux/utils/util-linux/. |