[리눅스마스터 1급 실기] 디스크 관련 정보 (UUID, blkid)

디스크 관련 정보

UUID(Universally Unique Identifier)

• 범용 고유 식별자라고 불린다.
• 보통 여러 개체들이 존재하는 환경에서 식별하고 구별하기 위해 사용되는 고유한 이름을 통칭한다.
• 최근 리눅스에서 파티션을 생성하려면 고유한 UUID가 부여된다.
  • blkid 명령어를 사용해서 확인할 수 있다.

 

blkid

• 블록 장치(Block Device)의 속성 정보를 출력 하는 명령
• UUID, LABEL 등을 확인할 수 있다.

 

사용법

$ blkid [option] [device]

 

주요 옵션

옵션	설명
-L	라벨(Label)) 명으로 블록 장치를 찾을 때 사용
-U	UUID 명으로 블록 장치를 찾을 때 사용

 

사용 예

• 블록 장치의 UUID 및 파일 시스템 정보 출력

# blkid

 

• /dev/sda1의 UUID 및 파일 시스템 정보 출력

$ blkid /dev/sda1

 

• UUID가 c2798900-527e-4d78-9cd0-3e0f952482ef인 블록 장치를 찾아서 출력

$ blkid -U c2798900-527e-4d78-9cd0-3e0f952482ef

 

문제 해결 전략

• blkid 명령어를 사용하여 하드디스크 등 디스크 관련 정보를 확인하는 문제가 출제된다.
• man blkid 명령을 사용하여 메뉴얼을 확인하면서 문제를 해결한다.

 

$ man blkid

BLKID(8)                                  System Administration                                  BLKID(8)



NAME
       blkid - locate/print block device attributes

SYNOPSIS
       blkid -L label | -U uuid

       blkid [-dghlv] [-c file] [-o format] [-s tag]
             [-t NAME=value] [device ...]

       blkid -p [-O offset] [-o format] [-S size] [-s tag]
                [-n list] [-u list] device ...

       blkid -i [-o format] [-s tag] device ...


DESCRIPTION
       The  blkid  program is the command-line interface to working with the 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).

       It is recommended to use lsblk(8) command to get information about block devices, or lsblk --fs to
       get an overview of filesystems, or findmnt(8) to search in already mounted filesystems.

              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.  blkid reads
              information directly from devices and for  non-root  users  it  returns  cached  unverified
              information.  blkid is mostly designed for system services and to test libblkid functional‐
              ity.

       When device is specified, tokens from only this device are displayed.  It is possible  to  specify
       multiple  device  arguments  on  the  command line.  If none is given, all devices which appear in
       /proc/partitions are shown, if they are recognized.

       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  blkid  silently ignores all devices where the probing result is ambivalent
       (multiple colliding filesystems are detected).  The low-level  probing  mode  (-p)  provides  more
       information  and  extra  return  code  in  this  case.  It's recommended to use wipefs(8) to get a
       detailed overview and to erase obsolete stuff (magic strings) from the device.

OPTIONS
       The size and offset 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.

       -c cachefile
              Read  from  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 /dev/null.

       -d     Don't  encode non-printing characters.  The non-printing characters are encoded by ^ and M-
              notation by default.  Note that the -o udev output format uses a different  encoding  which
              cannot be disabled.

       -g     Perform  a  garbage  collection  pass  on the blkid cache to remove devices which no longer
              exist.

       -h     Display a usage message and exit.

       -i     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 -p option.

       -k     List all known filesystems and RAIDs and exit.

       -l     Look up only one device that matches the search parameter specified with the -t 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, blkid will print all of the
              devices that match the search parameter.

       -L label
              Look up the device that uses this filesystem label; this  is  equal  to  -l  -o  device  -t
              LABEL=label.   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 -L option works on systems with and
              without udev.

              Unfortunately, the original blkid(8) from e2fsprogs uses the -L option as a synonym for  -o
              list.   For better portability, use -l -o device -t LABEL=label and -o list in your scripts
              rather than the -L option.

       -n list
              Restrict the probing functions to the specified (comma-separated) list of superblock  types
              (names).   The  list  items  may be prefixed with "no" to specify the types which should be
              ignored.  For example:

                blkid -p -n vfat,ext3,ext4 /dev/sda1

              probes for vfat, ext3 and ext4 filesystems, and

                blkid -p -n nominix /dev/sda1

              probes for all supported formats except minix filesystems.   This  option  is  only  useful
              together with -p.

       -o format
              Use  the  specified  output  format.   Note  that the order of variables and devices is not
              fixed.  See also option -s.  The format parameter may be:

              full   print all tags (the default)

              value  print the value of the tags

              list   print the devices in a user-friendly format; this output format is  unsupported  for
                     low-level probing (-p or -i).

                     This output format is DEPRECATED in favour of the lsblk(8) command.

              device print  the  device name only; this output format is always enabled for the -L and -U
                     options

              udev   print key="value" pairs for easy import into the udev environment; the keys are pre‐
                     fixed by ID_FS_ or ID_PART_ prefixes

                     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 par‐
                     titions.  This output format is DEPRECATED.

              export print  key=value  pairs  for easy import into the environment; this output format is
                     automatically enabled when I/O Limits (-i option) are requested

       -O offset
              Probe at the given offset (only useful with -p).  This option can be used together with the
              -i option.

       -p     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).

       -s tag For each (specified) device, show only the tags 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.

       -S size
              Override the size of device/file (only useful with -p).

       -t NAME=value
              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 the specified devices are searched.

       -u list
              Restrict the probing functions to the specified (comma-separated) list  of  "usage"  types.
              Supported  usage types are: filesystem, raid, crypto and other.  The list items may be pre‐
              fixed with "no" to specify the usage types which should be ignored.  For example:

                blkid -p -u filesystem,other /dev/sda1

              probes for all filesystem and other (e.g. swap) formats, and

                blkid -p -u noraid /dev/sda1

              probes for all supported formats except RAIDs.  This option is only  useful  together  with
              -p.

       -U uuid
              Look up the device that uses this filesystem uuid.  For more details see the -L option.

       -V     Display version number and exit.

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.

       If  an ambivalent probing result was detected by low-level probing mode (-p), an exit code of 8 is
       returned.

CONFIGURATION FILE
       The standard location of the /etc/blkid.conf config file can  be  overridden  by  the  environment
       variable BLKID_CONF.  The following options control the libblkid library:

       SEND_UEVENT=<yes|not>
              Sends uevent when /dev/disk/by-{label,uuid,partuuid,partlabel}/ symlink does not match with
              LABEL, UUID, PARTUUID or PARTLABEL on the device.  Default is "yes".

       CACHE_FILE=<path>
              Overrides the standard location of the cache file.  This setting can be overridden  by  the
              environment  variable  BLKID_FILE.   Default  is /run/blkid/blkid.tab, or /etc/blkid.tab on
              systems without a /run directory.

       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 /dev/disk/by-* symlinks and the
              "scan" method scans all block devices from the /proc/partitions file.

AUTHOR
       blkid was written by Andreas Dilger for libblkid and improved by Theodore Ts'o and Karel Zak.

ENVIRONMENT
       Setting LIBBLKID_DEBUG=0xffff enables debug output.

SEE ALSO
       libblkid(3), findfs(8), wipefs(8)

AVAILABILITY
       The  blkid  command  is  part  of  the  util-linux  package  and  is available from ftp://ftp.ker‐
       nel.org/pub/linux/utils/util-linux/.



util-linux                                      March 2013                                       BLKID(8)

 

 

문제 유형

① 하드디스크 관리에 관한 문제

가. 디스크 파티션 UUID를 출력한다.
# (  blkid )

나. /dev/sda1의 I/O 제한 정보를 출력한다.
# (  blkid  ) (  -i  )

 

② 디스크 관련 정보를 확인하는 문제

가. /dev/sda1에 부여되어 있는 UUID 값을 출력한다.
# (  blkid  ) /dev/sda1

나. /dev/sda1의 블록 사이즈 정보를 출력한다.
# (  dumpe2fs  ) /dev/sda1