Examples of chown

• Change the ownership to dodo and the group dodo on a file named test.txt
  chown dodo:dodo test.txt

Man Page of chown

NAME
       chown - change file owner and group

SYNOPSIS
       chown [OPTION]... [OWNER][:[GROUP]] FILE...
       chown [OPTION]... --reference=RFILE FILE...

DESCRIPTION
       This manual page documents the GNU version of chown.  chown changes the
       user and/or group ownership of each given file.  If only  an  owner  (a
       user  name or numeric user ID) is given, that user is made the owner of
       each given file, and the files' group is not changed.  If the owner  is
       followed  by  a  colon  and a group name (or numeric group ID), with no
       spaces between them, the group ownership of the  files  is  changed  as
       well.  If a colon but no group name follows the user name, that user is
       made the owner of the files and the group of the files  is  changed  to
       that  user's  login  group.   If the colon and group are given, but the
       owner is omitted, only the group of the files is changed; in this case,
       chown  performs  the same function as chgrp.  If only a colon is given,
       or if the entire operand is empty, neither the owner nor the  group  is
       changed.

OPTIONS
       Change the owner and/or group of each FILE to OWNER and/or GROUP.  With
       --reference, change the owner and group of each FILE to those of RFILE.

       -c, --changes
              like verbose but report only when a change is made

       --dereference
              affect the referent of each symbolic link (this is the default),
              rather than the symbolic link itself

       -h, --no-dereference
              affect each symbolic link instead of any referenced file (useful
              only on systems that can change the ownership of a symlink)

       --from=CURRENT_OWNER:CURRENT_GROUP
              change  the  owner and/or group of each file only if its current
              owner and/or group match those specified here.   Either  may  be
              omitted,  in  which case a match is not required for the omitted
              attribute.

       --no-preserve-root
              do not treat `/' specially (the default)

       --preserve-root
              fail to operate recursively on `/'

       -f, --silent, --quiet
              suppress most error messages

       --reference=RFILE
              use RFILE's owner and group rather than  specifying  OWNER:GROUP
              values

       -R, --recursive
              operate on files and directories recursively

       -v, --verbose
              output a diagnostic for every file processed

       The  following  options modify how a hierarchy is traversed when the -R
       option is also specified.  If more than  one  is  specified,  only  the
       final one takes effect.

       -H     if  a  command  line argument is a symbolic link to a directory,
              traverse it

       -L     traverse every symbolic link to a directory encountered

       -P     do not traverse any symbolic links (default)

       --help display this help and exit

       --version
              output version information and exit

       Owner is unchanged if missing.  Group  is  unchanged  if  missing,  but
       changed  to login group if implied by a `:' following a symbolic OWNER.
       OWNER and GROUP may be numeric as well as symbolic.

EXAMPLES
       chown root /u
              Change the owner of /u to "root".

       chown root:staff /u
              Likewise, but also change its group to "staff".

       chown -hR root /u
              Change the owner of /u and subfiles to "root".

AUTHOR
       Written by David MacKenzie and Jim Meyering.

REPORTING BUGS
       Report chown bugs to bug-coreutils@gnu.org
       GNU coreutils home page:
       General help using GNU software:

COPYRIGHT
       Copyright © 2009 Free Software Foundation, Inc.   License  GPLv3+:  GNU
       GPL version 3 or later .
       This  is  free  software:  you  are free to change and redistribute it.
       There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
       chown(2)

       The full documentation for chown is maintained as a Texinfo manual.  If
       the  info  and  chown programs are properly installed at your site, the
       command

              info coreutils 'chown invocation'

       should give you access to the complete manual.



GNU coreutils 7.1                October 2009                         CHOWN(1)





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Man Page of quotaon

NAME
       quotaon, quotaoff - turn filesystem quotas on and off

SYNOPSIS
       /sbin/quotaon [ -vugfp ] [ -F format-name ] filesystem...
       /sbin/quotaon [ -avugfp ] [ -F format-name ]

       /sbin/quotaoff [ -vugp ] [ -x state ] filesystem...
       /sbin/quotaoff [ -avugp ]

DESCRIPTION
   quotaon
       quotaon  announces  to the system that disk quotas should be enabled on
       one or more filesystems. The filesystem quota files must be present  in
       the  root  directory  of  the  specified filesystem and be named either
       aquota.user (for version 2 user quota), quota.user (for version 1  user
       quota),  aquota.group  (for version 2 group quota), or quota.group (for
       version 1 group quota).

       XFS filesystems are a special case - XFS considers quota information as
       filesystem metadata and uses journaling to provide a higher level guar-
       antee of consistency.  There are two components to the XFS  disk  quota
       system: accounting and limit enforcement.  XFS filesystems require that
       quota accounting be turned on at mount time.  It is possible to  enable
       and disable limit enforcement on an XFS filesystem after quota account-
       ing is already turned on.  The default is to turn  on  both  accounting
       and enforcement.

       The  XFS  quota  implementation  does not maintain quota information in
       user-visible files, but rather stores this information internally.

   quotaoff
       quotaoff announces to the system that the specified filesystems  should
       have any disk quotas turned off.

OPTIONS
   quotaon
       -F, --format=format-name
              Report  quota  for  specified  format  (ie. don't perform format
              autodetection).  Possible format names are:  vfsold  (version  1
              quota), vfsv0 (version 2 quota), xfs (quota on XFS filesystem)

       -a, --all
              All automatically mounted (no noauto option) non-NFS filesystems
              in /etc/fstab with quotas will  have  their  quotas  turned  on.
              This is normally used at boot time to enable quotas.

       -v, --verbose
              Display  a  message  for each filesystem where quotas are turned
              on.

       -u, --user
              Manipulate user quotas. This is the default.

       -g, --group
              Manipulate group quotas.

       -p, --print-state
              Instead of turning quotas on just print  state  of  quotas  (ie.
              whether. quota is on or off)

       -f, --off
              Make quotaon behave like being called as quotaoff.

   quotaoff
       -F, --format=format-name
              Report  quota  for  specified  format  (ie. don't perform format
              autodetection).  Possible format names are:  vfsold  (version  1
              quota), vfsv0 (version 2 quota), xfs (quota on XFS filesystem)

       -a, --all
              Force  all  filesystems  in /etc/fstab to have their quotas dis-
              abled.

       -v, --verbose
              Display a message for each filesystem affected.

       -u, --user
              Manipulate user quotas. This is the default.

       -g, --group
              Manipulate group quotas.

       -p, --print-state
              Instead of turning quotas off just print state  of  quotas  (ie.
              whether. quota is on or off)

       -x, --xfs-command delete
              Free  up  the  space  used to hold quota information (maintained
              internally) within XFS.  This option is only applicable to  XFS,
              and is silently ignored for other filesystem types.  It can only
              be used on a filesystem with quota previously turned off.

       -x, --xfs-command enforce
              Switch on/off limit enforcement  for  XFS  filesystems  (perform
              quota  accounting only).  This option is only applicable to XFS,
              and is silently ignored for other filesystem types.

NOTES ON XFS FILESYSTEMS
       To enable quotas on an XFS filesystem, use mount(8) or /etc/fstab quota
       option  to enable both accounting and limit enforcement.  quotaon util-
       ity cannot be used for this purpose.

       Turning on quotas on an XFS root filesystem requires  the  quota  mount
       options  be passed into the kernel at boot time through the Linux root-
       flags boot option.

       To turn off quota limit enforcement on any XFS filesystem,  first  make
       sure  that  quota  accounting  and enforcement are both turned on using
       repquota -v filesystem.  Then, use quotaoff -v  filesystem  to  disable
       limit enforcement.  This may be done while the filesystem is mounted.

       Turning  on  quota  limit  enforcement on an XFS filesystem is achieved
       using quotaon -v filesystem.  This may be done while the filesystem  is
       mounted.

FILES
       aquota.user or aquota.group
                           quota file at the filesystem root (version 2 quota,
                           non-XFS filesystems)
       quota.user or quota.group
                           quota file at the filesystem root (version 1 quota,
                           non-XFS filesystems)
       /etc/fstab          default filesystems

SEE ALSO
       quotactl(2), fstab(5), quota_nld(8), repquota(8), warnquota(8)



4th Berkeley Distribution                                           QUOTAON(8)


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Man Page of repquota

NAME
       repquota - summarize quotas for a filesystem

SYNOPSIS
       /usr/sbin/repquota [ -vspiug ] [ -c | -C ] [ -t | -n ] [ -F format-name
       ] filesystem...

       /usr/sbin/repquota [ -avtpsiug ] [ -c | -C ] [ -t | -n ] [  -F  format-
       name ]

DESCRIPTION
       repquota  prints  a summary of the disc usage and quotas for the speci-
       fied file systems.  For each user  the  current  number  of  files  and
       amount  of  space (in kilobytes) is printed, along with any quotas cre-
       ated with  edquota(8).   As  repquota  has  to  translate  ids  of  all
       users/groups  to  names  (unless option -n was specified) it may take a
       while to print all the information. To make translating as fast as pos-
       sible  repquota tries to detect (by reading /etc/nsswitch.conf) whether
       entries are stored in standard plain  text  file  or  in  database  and
       either  translates  chunks of 1024 names or each name individually. You
       can override this autodetection by -c or -C options.

OPTIONS
       -a, --all
              Report on all filesystems indicated in  /etc/mtab  to  be  read-
              write with quotas.

       -v, --verbose
              Report  all quotas, even if there is no usage. Be also more ver-
              bose about quotafile information.

       -c, --batch-translation
              Cache entries to report and translate uids/gids to names in  big
              chunks  by  scanning  all  users  (default). This is good (fast)
              behaviour when using /etc/passwd file.

       -C, --no-batch-translation
              Translate individual entries. This is faster when you have users
              stored in database.

       -t, --truncate-names
              Truncate user/group names longer than 9 characters. This results
              in nicer output when there are such names.

       -n, --no-names
              Don't resolve UIDs/GIDs to names. This can  speedup  printing  a
              lot.

       -s, --human-readable
              Try  to  report  used space, number of used inodes and limits in
              more appropriate units than the default ones.

       -p, --raw-grace
              When user is in grace period, report time in seconds since epoch
              when his grace time runs out (or has run out). Field is '0' when
              no grace time is in effect.   This  is  especially  useful  when
              parsing output by a script.

       -i, --no-autofs
              Ignore mountpoints mounted by automounter.

       -F, --format=format-name
              Report  quota  for  specified  format  (ie. don't perform format
              autodetection).  Possible format names are:  vfsold  (version  1
              quota), vfsv0 (version 2 quota), xfs (quota on XFS filesystem)

       -g, --group
              Report quotas for groups.

       -u, --user
              Report quotas for users. This is the default.

       Only the super-user may view quotas which are not their own.

FILES
       aquota.user or aquota.group
                           quota file at the filesystem root (version 2 quota,
                           non-XFS filesystems)
       quota.user or quota.group
                           quota file at the filesystem root (version 1 quota,
                           non-XFS filesystems)
       /etc/mtab           default filesystems
       /etc/passwd         default set of users
       /etc/group          default set of groups

SEE ALSO
       quota(1),    quotactl(2),    edquota(8),   quotacheck(8),   quotaon(8),
       quota_nld(8), setquota(8), warnquota(8)

4th Berkeley Distribution                                          REPQUOTA(8)


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Man Page of edquota

NAME
       edquota - edit user quotas

SYNOPSIS
       edquota  [  -p  protoname ] [ -u | -g ] [ -rm ] [ -F format-name ] [ -f
       filesystem ] username...

       edquota [ -u | -g ] [ -F format-name ] [ -f filesystem ] -t

       edquota [ -u | -g ] [ -F format-name ] [ -f filesystem ] -T  username |
       groupname...

DESCRIPTION
       edquota  is  a quota editor.  One or more users or groups may be speci-
       fied on the command line.  If  a  number  is  given  in  the  place  of
       user/group  name  it is treated as an UID/GID. For each user or group a
       temporary file is created with an ASCII representation of  the  current
       disk quotas for that user or group and an editor is then invoked on the
       file.  The quotas may then be modified, new quotas added, etc.  Setting
       a quota to zero indicates that no quota should be imposed.

       Users are permitted to exceed their soft limits for a grace period that
       may be specified per filesystem.  Once the grace  period  has  expired,
       the soft limit is enforced as a hard limit.

       The  current  usage  information  in the file is for informational pur-
       poses; only the hard and soft limits can be changed.

       Upon leaving the editor, edquota reads the temporary file and  modifies
       the binary quota files to reflect the changes made.

       The  editor  invoked  is  vi(1)  unless either the EDITOR or the VISUAL
       environment variable specifies otherwise.

       Only the super-user may edit quotas.

OPTIONS
       -r, --remote
              Edit also non-local quota use rpc.rquotad on  remote  server  to
              set  quota.   This  option is available only if quota tools were
              compiled with enabled support for setting quotas over RPC.   The
              -n option is equivalent, and is maintained for backward compati-
              bility.

       -m, --no-mixed-pathnames
              Currently, pathnames of NFSv4 mountpoints are sent without lead-
              ing slash in the path.  rpc.rquotad uses this to recognize NFSv4
              mounts and properly prepend pseudoroot of NFS filesystem to  the
              path.  If  you  specify  this  option, setquota will always send
              paths with a trailing slash. This can be useful for legacy  rea-
              sons  but  be aware that quota over RPC will stop working if you
              are using new rpc.rquotad.

       -u, --user
              Edit the user quota. This is the default.

       -g, --group
              Edit the group quota.

       -p, --prototype=protoname
              Duplicate the quotas of the prototypical user specified for each
              user specified.  This is the normal mechanism used to initialize
              quotas for groups of users.

       -F, --format=format-name
              Edit quota  for  specified  format  (ie.  don't  perform  format
              autodetection).   Possible  format  names are: vfsold (version 1
              quota), vfsv0 (version 2  quota),  rpc  (quota  over  NFS),  xfs
              (quota on XFS filesystem)

       -f, --filesystem filesystem
              Perform  specified operations only for given filesystem (default
              is to perform operations for all filesystems with quota).

       -t, --edit-period
              Edit the soft time limits for each  filesystem.   In  old  quota
              format  if  the time limits are zero, the default time limits in
              are used. In new quota format time  limits  must
              be  specified  (there  is  no default value set in kernel). Time
              units of 'seconds', 'minutes', 'hours', and  'days'  are  under-
              stood.  Time  limits  are  printed in the greatest possible time
              unit such that the value is greater than or equal to one.

       -T, --edit-times
              Edit time for the user/group when softlimit is enforced.  Possi-
              ble values are 'unset' or number and unit. Units are the same as
              in -t option.

FILES
       aquota.user or aquota.group
                           quota file at the filesystem root (version 2 quota,
                           non-XFS filesystems)
       quota.user or quota.group
                           quota file at the filesystem root (version 1 quota,
                           non-XFS filesystems)
       /etc/mtab           mounted filesystems table

SEE ALSO
       quota(1), vi(1), quotactl(2), quotacheck(8),  quotaon(8),  repquota(8),
       setquota(8)


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Man Page of quota

QUOTA(1)                                                              QUOTA(1)



NAME
       quota - display disk usage and limits

SYNOPSIS
       quota [ -F format-name ] [ -guqvswi ] [ -l | [ -QAm ]]
       quota [ -F format-name ] [ -qvswi ] [ -l | [ -QAm ]] -u user...
       quota [ -F format-name ] [ -qvswi ] [ -l | [ -QAm ]] -g group...
       quota [ -F format-name ] [ -qvswugQm ] -f filesystem...

DESCRIPTION
       quota  displays users' disk usage and limits.  By default only the user
       quotas are printed.

       quota reports the quotas of all the filesystems  listed  in  /etc/mtab.
       For  filesystems  that are NFS-mounted a call to the rpc.rquotad on the
       server machine is performed to get the information.

OPTIONS
       -F, --format=format-name
              Show quota  for  specified  format  (ie.  don't  perform  format
              autodetection).   Possible  format  names are: vfsold (version 1
              quota), vfsv0 (version 2  quota),  rpc  (quota  over  NFS),  xfs
              (quota on XFS filesystem)

       -g, --group
              Print  group quotas for the group of which the user is a member.
              The optional group argument(s)  restricts  the  display  to  the
              specified group(s).

       -u, --user
              flag is equivalent to the default.

       -v, --verbose
              will  display  quotas  on  filesystems where no storage is allo-
              cated.

       -s, --human-readable
              option will make quota(1) try to choose units for  showing  lim-
              its, used space and used inodes.

       -p, --raw-grace
              When user is in grace period, report time in seconds since epoch
              when his grace time runs out (or has run out). Field is '0' when
              no  grace  time  is  in  effect.  This is especially useful when
              parsing output by a script.

       -i, --no-autofs
              ignore mountpoints mounted by automounter

       -l, --local-only
              report quotas only on local filesystems (ie. ignore NFS  mounted
              filesystems).

       -A, --all-nfs
              report  quotas for all NFS filesystems even if they report to be
              on the same device.

       -m, --no-mixed-pathnames
              Currently, pathnames of NFSv4 mountpoints are sent without lead-
              ing slash in the path.  rpc.rquotad uses this to recognize NFSv4
              mounts and properly prepend pseudoroot of NFS filesystem to  the
              path.  If  you  specify  this  option, setquota will always send
              paths with a trailing slash. This can be useful for legacy  rea-
              sons  but  be aware that quota over RPC will stop working if you
              are using new rpc.rquotad.

       -q, --quiet
              Print a more  terse  message,  containing  only  information  on
              filesystems where usage is over quota.

       -Q, --quiet-refuse
              Do  not  print  error  message  if  connection to rpc.rquotad is
              refused (usually this happens when rpc.rquotad is not running on
              the server).

       -w, --no-wrap
              Do not wrap the line if the device name is too long. This can be
              useful when parsing the output of quota(1) by a script.

       Specifying both -g and -u displays both the user quotas and  the  group
       quotas (for the user).

       Only  the super-user may use the -u flag and the optional user argument
       to view the limits of other users.  Non-super-users can use the the  -g
       flag  and  optional group argument to view only the limits of groups of
       which they are members.

       The -q flag takes precedence over the -v flag.

DIAGNOSTICS
       If quota exits with a non-zero status, one or more filesystems are over
       quota.

FILES
       aquota.user  or  aquota.group
                           quota file at the filesystem root (version 2 quota,
                           non-XFS filesystems)
       quota.user  or  quota.group
                           quota file at the filesystem root (version 1 quota,
                           non-XFS filesystems)
       /etc/mtab           default filesystems

SEE ALSO
       quotactl(2),    fstab(5),    edquota(8),   quotacheck(8),   quotaon(8),
       quota_nld(8), repquota(8),

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examples of grep

• Only display lines containing capital letters
  grep -n [A-Z] name.txt
•  

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Man Page of grep

NAME
       grep, egrep, fgrep - print lines matching a pattern

SYNOPSIS
       grep [OPTIONS] PATTERN [FILE...]
       grep [OPTIONS] [-e PATTERN | -f FILE] [FILE...]

DESCRIPTION
       grep  searches the named input FILEs (or standard input if no files are
       named, or if a single hyphen-minus (-) is given as file name) for lines
       containing  a  match to the given PATTERN.  By default, grep prints the
       matching lines.

       In addition, two variant programs egrep and fgrep are available.  egrep
       is  the  same  as  grep -E.   fgrep  is  the  same  as grep -F.  Direct
       invocation as either egrep or fgrep is deprecated, but is  provided  to
       allow historical applications that rely on them to run unmodified.

OPTIONS
   Generic Program Information
       --help Print  a  usage  message  briefly summarizing these command-line
              options and the bug-reporting address, then exit.

       -V, --version
              Print the version number of grep to the standard output  stream.
              This  version  number should be included in all bug reports (see
              below).

   Matcher Selection
       -E, --extended-regexp
              Interpret PATTERN as an extended regular  expression  (ERE,  see
              below).  (-E is specified by POSIX.)

       -F, --fixed-strings
              Interpret  PATTERN  as  a  list  of  fixed strings, separated by
              newlines, any of which is to be matched.  (-F  is  specified  by
              POSIX.)

       -G, --basic-regexp
              Interpret  PATTERN  as  a  basic  regular  expression  (BRE, see
              below).  This is the default.

       -P, --perl-regexp
              Interpret PATTERN as a Perl regular expression.  This is  highly
              experimental and grep -P may warn of unimplemented features.

   Matching Control
       -e PATTERN, --regexp=PATTERN
              Use  PATTERN  as  the  pattern.   This  can  be  used to specify
              multiple search patterns, or to protect a pattern beginning with
              a hyphen (-).  (-e is specified by POSIX.)

       -f FILE, --file=FILE
              Obtain  patterns  from  FILE,  one  per  line.   The  empty file
              contains zero patterns, and therefore matches nothing.   (-f  is
              specified by POSIX.)

       -i, --ignore-case
              Ignore  case  distinctions  in  both  the  PATTERN and the input
              files.  (-i is specified by POSIX.)

       -v, --invert-match
              Invert the sense of matching, to select non-matching lines.  (-v
              is specified by POSIX.)

       -w, --word-regexp
              Select  only  those  lines  containing  matches  that form whole
              words.  The test is that the matching substring must  either  be
              at  the  beginning  of  the  line,  or  preceded  by  a non-word
              constituent character.  Similarly, it must be either at the  end
              of  the  line  or  followed by a non-word constituent character.
              Word-constituent  characters  are  letters,  digits,   and   the
              underscore.

       -x, --line-regexp
              Select  only  those  matches  that exactly match the whole line.
              (-x is specified by POSIX.)

       -y     Obsolete synonym for -i.

   General Output Control
       -c, --count
              Suppress normal output; instead print a count of matching  lines
              for  each  input  file.  With the -v, --invert-match option (see
              below), count non-matching lines.  (-c is specified by POSIX.)

       --color[=WHEN], --colour[=WHEN]
              Surround  the  matched  (non-empty)  strings,  matching   lines,
              context  lines,  file  names,  line  numbers,  byte offsets, and
              separators (for fields and groups of context lines) with  escape
              sequences  to display them in color on the terminal.  The colors
              are  defined  by  the  environment  variable  GREP_COLORS.   The
              deprecated  environment  variable GREP_COLOR is still supported,
              but its setting does not have priority.  WHEN is never,  always,
              or auto.

       -L, --files-without-match
              Suppress  normal  output;  instead  print the name of each input
              file from which no output would normally have been printed.  The
              scanning will stop on the first match.

       -l, --files-with-matches
              Suppress  normal  output;  instead  print the name of each input
              file from which output would normally have  been  printed.   The
              scanning  will  stop  on  the  first match.  (-l is specified by
              POSIX.)

       -m NUM, --max-count=NUM
              Stop reading a file after NUM matching lines.  If the  input  is
              standard  input  from a regular file, and NUM matching lines are
              output, grep ensures that the standard input  is  positioned  to
              just  after the last matching line before exiting, regardless of
              the presence of trailing context lines.  This enables a  calling
              process  to resume a search.  When grep stops after NUM matching
              lines, it outputs any trailing context lines.  When  the  -c  or
              --count  option  is  also  used,  grep  does  not output a count
              greater than NUM.  When the -v or --invert-match option is  also
              used, grep stops after outputting NUM non-matching lines.

       -o, --only-matching
              Print  only  the  matched  (non-empty) parts of a matching line,
              with each such part on a separate output line.

       -q, --quiet, --silent
              Quiet;  do  not  write  anything  to  standard   output.    Exit
              immediately  with  zero status if any match is found, even if an
              error was detected.  Also see the -s  or  --no-messages  option.
              (-q is specified by POSIX.)

       -s, --no-messages
              Suppress  error  messages about nonexistent or unreadable files.
              Portability note: unlike GNU grep, 7th Edition Unix grep did not
              conform to POSIX, because it lacked -q and its -s option behaved
              like GNU grep's -q option.  USG-style grep also  lacked  -q  but
              its  -s  option  behaved  like GNU grep.  Portable shell scripts
              should avoid both -q and -s and  should  redirect  standard  and
              error  output to /dev/null instead.  (-s is specified by POSIX.)

   Output Line Prefix Control
       -b, --byte-offset
              Print the 0-based byte offset within the input file before  each
              line of output.  If -o (--only-matching) is specified, print the
              offset of the matching part itself.

       -H, --with-filename
              Print the file name for each match.  This is  the  default  when
              there is more than one file to search.

       -h, --no-filename
              Suppress  the  prefixing  of  file names on output.  This is the
              default when there is only one file (or only standard input)  to
              search.

       --label=LABEL
              Display  input  actually  coming  from  standard  input as input
              coming from file LABEL.  This is  especially  useful  for  tools
              like zgrep, e.g., gzip -cd foo.gz | grep --label=foo something

       -n, --line-number
              Prefix  each  line of output with the 1-based line number within
              its input file.  (-n is specified by POSIX.)

       -T, --initial-tab
              Make sure that the first character of actual line  content  lies
              on a tab stop, so that the alignment of tabs looks normal.  This
              is useful with options that prefix their output  to  the  actual
              content:  -H,-n,  and  -b.   In order to improve the probability
              that lines from a single file will all start at the same column,
              this also causes the line number and byte offset (if present) to
              be printed in a minimum size field width.

       -u, --unix-byte-offsets
              Report Unix-style byte offsets.   This  switch  causes  grep  to
              report  byte offsets as if the file were a Unix-style text file,
              i.e., with  CR  characters  stripped  off.   This  will  produce
              results  identical  to  running  grep  on  a Unix machine.  This
              option has no effect unless -b option is also used;  it  has  no
              effect on platforms other than MS-DOS and MS-Windows.

       -Z, --null
              Output  a  zero  byte  (the  ASCII NUL character) instead of the
              character that normally follows a file name.  For example,  grep
              -lZ  outputs  a  zero  byte  after each file name instead of the
              usual newline.  This option makes the output  unambiguous,  even
              in the presence of file names containing unusual characters like
              newlines.  This option can  be  used  with  commands  like  find
              -print0,  perl  -0,  sort  -z, and xargs -0 to process arbitrary
              file names, even those that contain newline characters.

   Context Line Control
       -A NUM, --after-context=NUM
              Print NUM  lines  of  trailing  context  after  matching  lines.
              Places   a  line  containing  a  group  separator  (--)  between
              contiguous groups of matches.  With the  -o  or  --only-matching
              option, this has no effect and a warning is given.

       -B NUM, --before-context=NUM
              Print  NUM  lines  of  leading  context  before  matching lines.
              Places  a  line  containing  a  group  separator  (--)   between
              contiguous  groups  of  matches.  With the -o or --only-matching
              option, this has no effect and a warning is given.

       -C NUM, -NUM, --context=NUM
              Print NUM lines of output context.  Places a line  containing  a
              group separator (--) between contiguous groups of matches.  With
              the -o or --only-matching option,  this  has  no  effect  and  a
              warning is given.

   File and Directory Selection
       -a, --text
              Process  a binary file as if it were text; this is equivalent to
              the --binary-files=text option.

       --binary-files=TYPE
              If the first few bytes of a file indicate that the file contains
              binary  data, assume that the file is of type TYPE.  By default,
              TYPE is binary, and grep  normally  outputs  either  a  one-line
              message  saying  that  a  binary  file matches, or no message if
              there is no match.  If TYPE is without-match, grep assumes  that
              a  binary  file  does  not  match;  this is equivalent to the -I
              option.  If TYPE is text, grep processes a binary file as if  it
              were  text;  this is equivalent to the -a option.  Warning: grep
              --binary-files=text might output binary garbage, which can  have
              nasty  side  effects  if  the  output  is  a terminal and if the
              terminal driver interprets some of it as commands.

       -D ACTION, --devices=ACTION
              If an input file is a device, FIFO  or  socket,  use  ACTION  to
              process  it.   By  default,  ACTION  is  read,  which means that
              devices are read just as if they were ordinary files.  If ACTION
              is skip, devices are silently skipped.

       -d ACTION, --directories=ACTION
              If  an  input file is a directory, use ACTION to process it.  By
              default, ACTION is read, which means that directories  are  read
              just  as  if  they  were  ordinary  files.   If  ACTION is skip,
              directories are silently skipped.  If ACTION  is  recurse,  grep
              reads  all  files  under  each  directory,  recursively; this is
              equivalent to the -r option.

       --exclude=GLOB
              Skip  files  whose  base  name  matches  GLOB  (using   wildcard
              matching).   A  file-name  glob  can  use  *,  ?,  and [...]  as
              wildcards, and \ to quote  a  wildcard  or  backslash  character
              literally.

       --exclude-from=FILE
              Skip  files  whose  base name matches any of the file-name globs
              read from FILE  (using  wildcard  matching  as  described  under
              --exclude).

       --exclude-dir=DIR
              Exclude  directories  matching  the  pattern  DIR from recursive
              searches.

       -I     Process a binary file as if it did not  contain  matching  data;
              this is equivalent to the --binary-files=without-match option.

       --include=GLOB
              Search  only  files whose base name matches GLOB (using wildcard
              matching as described under --exclude).

       -R, -r, --recursive
              Read all  files  under  each  directory,  recursively;  this  is
              equivalent to the -d recurse option.

   Other Options
       --line-buffered
              Use  line  buffering  on  output.   This can cause a performance
              penalty.

       --mmap If possible, use the mmap(2) system call to read input,  instead
              of  the default read(2) system call.  In some situations, --mmap
              yields better performance.  However, --mmap can cause  undefined
              behavior  (including  core dumps) if an input file shrinks while
              grep is operating, or if an I/O error occurs.

       -U, --binary
              Treat the file(s) as binary.  By default, under MS-DOS  and  MS-
              Windows,  grep  guesses the file type by looking at the contents
              of the first 32KB read from the file.  If grep decides the  file
              is  a  text  file, it strips the CR characters from the original
              file contents (to make regular expressions with  ^  and  $  work
              correctly).  Specifying -U overrules this guesswork, causing all
              files to be read and passed to the matching mechanism  verbatim;
              if  the  file is a text file with CR/LF pairs at the end of each
              line, this will cause some regular expressions  to  fail.   This
              option  has  no  effect  on  platforms other than MS-DOS and MS-
              Windows.

       -z, --null-data
              Treat the input as a set of lines, each  terminated  by  a  zero
              byte  (the  ASCII NUL character) instead of a newline.  Like the
              -Z or --null option, this option can be used with commands  like
              sort -z to process arbitrary file names.

REGULAR EXPRESSIONS
       A  regular  expression  is  a  pattern that describes a set of strings.
       Regular  expressions  are   constructed   analogously   to   arithmetic
       expressions, by using various operators to combine smaller expressions.

       grep understands two different versions of regular  expression  syntax:
       “basic”  and  “extended.”   In  GNU grep,  there  is  no  difference in
       available functionality using either syntax.  In other implementations,
       basic regular expressions are less powerful.  The following description
       applies to extended regular expressions; differences for basic  regular
       expressions are summarized afterwards.

       The  fundamental building blocks are the regular expressions that match
       a single character.  Most characters, including all letters and digits,
       are regular expressions that match themselves.  Any meta-character with
       special meaning may be quoted by preceding it with a backslash.

       The period . matches any single character.

   Character Classes and Bracket Expressions
       A bracket expression is a list of characters enclosed by [ and  ].   It
       matches  any  single  character in that list; if the first character of
       the list is the caret ^ then it matches any character not in the  list.
       For  example,  the  regular  expression [0123456789] matches any single
       digit.

       Within a  bracket  expression,  a  range  expression  consists  of  two
       characters separated by a hyphen.  It matches any single character that
       sorts  between  the  two  characters,  inclusive,  using  the  locale's
       collating  sequence  and  character set.  For example, in the default C
       locale, [a-d] is equivalent to [abcd].  Many locales sort characters in
       dictionary   order,  and  in  these  locales  [a-d]  is  typically  not
       equivalent to [abcd]; it might be equivalent to [aBbCcDd], for example.
       To  obtain  the  traditional interpretation of bracket expressions, you
       can use the C locale by setting the LC_ALL environment variable to  the
       value C.

       Finally,  certain  named  classes  of  characters are predefined within
       bracket expressions, as follows.  Their names are self explanatory, and
       they   are   [:alnum:],  [:alpha:],  [:cntrl:],  [:digit:],  [:graph:],
       [:lower:], [:print:], [:punct:], [:space:], [:upper:], and  [:xdigit:].
       For  example,  [[:alnum:]]  means  [0-9A-Za-z],  except the latter form
       depends upon the C locale and the ASCII character encoding, whereas the
       former  is  independent  of  locale  and character set.  (Note that the
       brackets in these class names are part of the symbolic names, and  must
       be  included  in  addition  to  the  brackets  delimiting  the  bracket
       expression.)  Most meta-characters lose their  special  meaning  inside
       bracket  expressions.   To  include  a  literal ] place it first in the
       list.  Similarly, to include a literal ^ place it anywhere  but  first.
       Finally, to include a literal - place it last.

   Anchoring
       The caret ^ and the dollar sign $ are meta-characters that respectively
       match the empty string at the beginning and end of a line.

   The Backslash Character and Special Expressions
       The symbols \< and \>  respectively  match  the  empty  string  at  the
       beginning and end of a word.  The symbol \b matches the empty string at
       the edge of a word, and \B matches the empty string provided  it's  not
       at  the edge of a word.  The symbol \w is a synonym for [[:alnum:]] and
       \W is a synonym for [^[:alnum:]].

   Repetition
       A regular expression may be  followed  by  one  of  several  repetition
       operators:
       ?      The preceding item is optional and matched at most once.
       *      The preceding item will be matched zero or more times.
       +      The preceding item will be matched one or more times.
       {n}    The preceding item is matched exactly n times.
       {n,}   The preceding item is matched n or more times.
       {,m}   The preceding item is matched at most m times.
       {n,m}  The  preceding  item  is  matched at least n times, but not more
              than m times.

   Concatenation
       Two regular expressions may  be  concatenated;  the  resulting  regular
       expression  matches  any  string formed by concatenating two substrings
       that respectively match the concatenated expressions.

   Alternation
       Two regular expressions may be joined by  the  infix  operator  |;  the
       resulting   regular  expression  matches  any  string  matching  either
       alternate expression.

   Precedence
       Repetition takes precedence over concatenation,  which  in  turn  takes
       precedence  over  alternation.   A  whole expression may be enclosed in
       parentheses  to  override   these   precedence   rules   and   form   a
       subexpression.

   Back References and Subexpressions
       The back-reference \n, where n is a single digit, matches the substring
       previously matched  by  the  nth  parenthesized  subexpression  of  the
       regular expression.

   Basic vs Extended Regular Expressions
       In  basic  regular expressions the meta-characters ?, +, {, |, (, and )
       lose their special meaning; instead use the  backslashed  versions  \?,
       \+, \{, \|, \(, and \).

       Traditional  egrep did not support the { meta-character, and some egrep
       implementations support \{ instead, so portable scripts should avoid  {
       in grep -E patterns and should use [{] to match a literal {.

       GNU grep -E attempts to support traditional usage by assuming that { is
       not  special  if  it  would  be  the  start  of  an  invalid   interval
       specification.   For example, the command grep -E '{1' searches for the
       two-character string {1 instead of reporting  a  syntax  error  in  the
       regular  expression.  POSIX.2 allows this behavior as an extension, but
       portable scripts should avoid it.

ENVIRONMENT VARIABLES
       The  behavior  of  grep  is  affected  by  the  following   environment
       variables.

       The  locale  for  category  LC_foo  is specified by examining the three
       environment variables LC_ALL, LC_foo, LANG, in that order.   The  first
       of  these  variables that is set specifies the locale.  For example, if
       LC_ALL is not set, but LC_MESSAGES is set to pt_BR, then the  Brazilian
       Portuguese  locale  is used for the LC_MESSAGES category.  The C locale
       is used if none of these environment variables are set, if  the  locale
       catalog  is  not  installed,  or if grep was not compiled with national
       language support (NLS).

       GREP_OPTIONS
              This variable specifies default options to be placed in front of
              any   explicit   options.    For  example,  if  GREP_OPTIONS  is
              '--binary-files=without-match --directories=skip', grep  behaves
              as   if   the   two   options  --binary-files=without-match  and
              --directories=skip  had  been  specified  before  any   explicit
              options.   Option specifications are separated by whitespace.  A
              backslash escapes the next character,  so  it  can  be  used  to
              specify an option containing whitespace or a backslash.

       GREP_COLOR
              This  variable  specifies  the  color  used to highlight matched
              (non-empty) text.  It is deprecated in favor of GREP_COLORS, but
              still supported.  The mt, ms, and mc capabilities of GREP_COLORS
              have priority over it.  It can only specify the  color  used  to
              highlight  the  matching  non-empty text in any matching line (a
              selected line when the -v command-line option is omitted,  or  a
              context line when -v is specified).  The default is 01;31, which
              means a bold red  foreground  text  on  the  terminal's  default
              background.

       GREP_COLORS
              Specifies  the  colors  and  other  attributes used to highlight
              various parts of the output.  Its  value  is  a  colon-separated
              list       of       capabilities      that      defaults      to
              ms=01;31:mc=01;31:sl=:cx=:fn=35:ln=32:bn=32:se=36  with  the  rv
              and  ne  boolean  capabilities omitted (i.e., false).  Supported
              capabilities are as follows.

              sl=    SGR substring for whole selected  lines  (i.e.,  matching
                     lines when the -v command-line option is omitted, or non-
                     matching lines when -v is  specified).   If  however  the
                     boolean  rv capability and the -v command-line option are
                     both specified, it  applies  to  context  matching  lines
                     instead.   The  default  is  empty  (i.e., the terminal's
                     default color pair).

              cx=    SGR substring for whole context lines (i.e., non-matching
                     lines  when  the  -v  command-line  option is omitted, or
                     matching lines when -v is  specified).   If  however  the
                     boolean  rv capability and the -v command-line option are
                     both specified, it applies to selected non-matching lines
                     instead.   The  default  is  empty  (i.e., the terminal's
                     default color pair).

              rv     Boolean value that reverses (swaps) the meanings  of  the
                     sl=  and cx= capabilities when the -v command-line option
                     is specified.  The default is false (i.e., the capability
                     is omitted).

              mt=01;31
                     SGR substring for matching non-empty text in any matching
                     line (i.e., a selected  line  when  the  -v  command-line
                     option   is  omitted,  or  a  context  line  when  -v  is
                     specified).  Setting this is equivalent to  setting  both
                     ms=  and mc= at once to the same value.  The default is a
                     bold  red  text  foreground   over   the   current   line
                     background.

              ms=01;31
                     SGR  substring  for matching non-empty text in a selected
                     line.  (This is only used when the -v command-line option
                     is  omitted.)   The  effect  of  the  sl=  (or cx= if rv)
                     capability  remains  active  when  this  kicks  in.   The
                     default  is  a  bold red text foreground over the current
                     line background.

              mc=01;31
                     SGR substring for matching non-empty text  in  a  context
                     line.  (This is only used when the -v command-line option
                     is specified.)  The effect of the  cx=  (or  sl=  if  rv)
                     capability  remains  active  when  this  kicks  in.   The
                     default is a bold red text foreground  over  the  current
                     line background.

              fn=35  SGR  substring for file names prefixing any content line.
                     The  default  is  a  magenta  text  foreground  over  the
                     terminal's default background.

              ln=32  SGR  substring  for  line  numbers  prefixing any content
                     line.  The default is a green text  foreground  over  the
                     terminal's default background.

              bn=32  SGR  substring  for  byte  offsets  prefixing any content
                     line.  The default is a green text  foreground  over  the
                     terminal's default background.

              se=36  SGR  substring  for  separators that are inserted between
                     selected line fields (:), between  context  line  fields,
                     (-),  and  between  groups of adjacent lines when nonzero
                     context is specified (--).  The default is  a  cyan  text
                     foreground over the terminal's default background.

              ne     Boolean  value  that prevents clearing to the end of line
                     using Erase in Line (EL) to Right  (\33[K)  each  time  a
                     colorized  item  ends.   This  is  needed on terminals on
                     which EL is not supported.  It  is  otherwise  useful  on
                     terminals  for  which  the back_color_erase (bce) boolean
                     terminfo capability  does  not  apply,  when  the  chosen
                     highlight colors do not affect the background, or when EL
                     is too slow or causes too much flicker.  The  default  is
                     false (i.e., the capability is omitted).

              Note  that  boolean  capabilities  have no =...  part.  They are
              omitted (i.e., false) by default and become true when specified.

              See   the   Select   Graphic  Rendition  (SGR)  section  in  the
              documentation of the text terminal that is  used  for  permitted
              values   and  their  meaning  as  character  attributes.   These
              substring values are integers in decimal representation and  can
              be  concatenated with semicolons.  grep takes care of assembling
              the result into a  complete  SGR  sequence  (\33[...m).   Common
              values to concatenate include 1 for bold, 4 for underline, 5 for
              blink, 7 for inverse, 39 for default foreground color, 30 to  37
              for  foreground  colors,  90  to 97 for 16-color mode foreground
              colors, 38;5;0 to 38;5;255  for  88-color  and  256-color  modes
              foreground colors, 49 for default background color, 40 to 47 for
              background colors, 100  to  107  for  16-color  mode  background
              colors,  and 48;5;0 to 48;5;255 for 88-color and 256-color modes
              background colors.

       LC_ALL, LC_COLLATE, LANG
              These variables specify the locale for the LC_COLLATE  category,
              which  determines the collating sequence used to interpret range
              expressions like [a-z].

       LC_ALL, LC_CTYPE, LANG
              These variables specify the locale for  the  LC_CTYPE  category,
              which  determines the type of characters, e.g., which characters
              are whitespace.

       LC_ALL, LC_MESSAGES, LANG
              These variables specify the locale for the LC_MESSAGES category,
              which  determines the language that grep uses for messages.  The
              default C locale uses American English messages.

       POSIXLY_CORRECT
              If set,  grep  behaves  as  POSIX.2  requires;  otherwise,  grep
              behaves  more  like  other  GNU programs.  POSIX.2 requires that
              options that follow file names must be treated as file names; by
              default,  such  options are permuted to the front of the operand
              list and are treated as options.  Also,  POSIX.2  requires  that
              unrecognized  options  be diagnosed as “illegal”, but since they
              are not really against the law the default is to  diagnose  them
              as      “invalid”.       POSIXLY_CORRECT      also      disables
              _N_GNU_nonoption_argv_flags_, described below.

       _N_GNU_nonoption_argv_flags_
              (Here N is grep's numeric process ID.)  If the ith character  of
              this  environment variable's value is 1, do not consider the ith
              operand of grep to be an option, even if it appears to  be  one.
              A  shell  can  put  this  variable  in  the environment for each
              command it runs, specifying which operands are  the  results  of
              file name wildcard expansion and therefore should not be treated
              as options.  This behavior is available  only  with  the  GNU  C
              library, and only when POSIXLY_CORRECT is not set.

EXIT STATUS
       Normally,  the  exit  status  is  0  if  selected lines are found and 1
       otherwise.  But the exit status is 2 if an error occurred,  unless  the
       -q  or --quiet or --silent option is used and a selected line is found.
       Note, however, that POSIX only mandates, for  programs  such  as  grep,
       cmp, and diff, that the exit status in case of error be greater than 1;
       it is therefore advisable, for the sake of portability,  to  use  logic
       that  tests  for  this  general  condition  instead  of strict equality
       with 2.

COPYRIGHT
       Copyright © 1998, 1999, 2000, 2002, 2005 Free Software Foundation, Inc.

       This is free software; see the source for copying conditions.  There is
       NO warranty; not even for MERCHANTABILITY or FITNESS FOR  A  PARTICULAR
       PURPOSE.

BUGS
   Reporting Bugs
       Email  bug reports to , a mailing list whose web page
       is .   grep's  Savannah
       bug tracker is located at .

   Known Bugs
       Large  repetition  counts  in the {n,m} construct may cause grep to use
       lots of memory.  In addition, certain other obscure regular expressions
       require  exponential  time  and space, and may cause grep to run out of
       memory.

       Back-references are very slow, and may require exponential time.

SEE ALSO
   Regular Manual Pages
       awk(1), cmp(1), diff(1), find(1), gzip(1),  perl(1),  sed(1),  sort(1),
       xargs(1),   zgrep(1),   mmap(2),   read(2),   pcre(3),  pcrepattern(3),
       terminfo(5), glob(7), regex(7).

   POSIX Programmer's Manual Page
       grep(1p).

   TeXinfo Documentation
       The full documentation for grep is maintained as a TeXinfo manual.   If
       the  info  and  grep  programs are properly installed at your site, the
       command

              info grep

       should give you access to the complete manual.

NOTES
       GNU's not Unix, but Unix is a beast; its plural form is Unixen.



GNU grep 2.5.1-cvs                2008-02-07                           GREP(1)



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