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grep(1)                                                                grep(1)




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 for lines containing a match to the
       given PATTERN.  If no files are specified, or if the file "-" is given,
       grep  searches  standard  input.   By default, grep prints the matching
       lines.

       In addition, the variant programs egrep  and  fgrep  are  the  same  as
       grep -E  and grep -F, respectively.  These variants are deprecated, but
       are provided for backward compatibility.


OPTIONS

   Generic Program Information
       --help Output a usage message and exit.

       -V, --version
              Output the version number of grep and exit.

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

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

       -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 (-).

       -f FILE, --file=FILE
              Obtain patterns  from  FILE,  one  per  line.   The  empty  file
              contains zero patterns, and therefore matches nothing.

       -i, --ignore-case
              Ignore  case  distinctions  in  both  the  PATTERN and the input
              files.

       -v, --invert-match
              Invert the sense of matching, to select non-matching lines.

       -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.

       -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.

       --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.

       -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.

       -s, --no-messages
              Suppress error messages about nonexistent or unreadable files.

   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  when
              implementing tools like zgrep, e.g.,  gzip  -cd  foo.gz  |  grep
              --label=foo -H something.  See also the -H option.

       -n, --line-number
              Prefix  each  line of output with the 1-based line number within
              its input file.

       -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, i.e., read directories just as if  they
              were   ordinary   files.   If  ACTION  is  skip,  silently  skip
              directories.  If ACTION is recurse, read all  files  under  each
              directory,  recursively,  following  symbolic links only if they
              are on the command line.  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, --recursive
              Read all files  under  each  directory,  recursively,  following
              symbolic  links  only  if they are on the command line.  This is
              equivalent to the -d recurse option.

       -R, --dereference-recursive
              Read all files under each directory,  recursively.   Follow  all
              symbolic links, unlike -r.

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

       -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 three different versions of regular expression syntax:
       "basic,"  "extended" and "perl." In GNU grep, there is no difference in
       available functionality between basic and extended syntaxes.  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.
       Perl  regular  expressions  give  additional  functionality,  and   are
       documented   in  pcresyntax(3)  and  pcrepattern(3),  but  may  not  be
       available on every system.

       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  the  character  class  of  numbers  and
       letters  in the current locale. In the C locale and ASCII character set
       encoding, this is the same as [0-9A-Za-z].  (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.  This  is  a  GNU
              extension.
       {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  \?,
       \+, \{, \|, \(, and \).


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.  As  this  causes  problems  when  writing
              portable  scripts,  this  feature  will  be  removed in a future
              release of grep, and grep warns if it is used.   Please  use  an
              alias or script instead.

       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 requires; otherwise, grep  behaves
              more  like other GNU programs.  POSIX 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 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 a line is selected, 1 if no lines were
       selected, and 2 if an error occurred.  However, if the -q or --quiet or
       --silent  is  used and a line is selected, the exit status is 0 even if
       an error occurred.


COPYRIGHT

       Copyright 1998-2000, 2002, 2005-2014 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

       the bug-reporting address <bug-grep@gnu.org>.  An email archive
       <http://lists.gnu.org/mailman/listinfo/bug-grep> and a bug tracker
       <http://debbugs.gnu.org/cgi/pkgreport.cgi?package=grep> are  available.

   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),
       grep(1),  read(2),  pcre(3), pcresyntax(3), pcrepattern(3),
       terminfo(5), glob(7), regex(7).

   POSIX Programmer's Manual Page
       grep(1).

   Full Documentation
       A   complete   manual   <http://www.gnu.org/software/grep/manual/>   is
       available.   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

       This man page is maintained only fitfully; the  full  documentation  is
       often more up-to-date.



User Commands                    GNU grep 2.21                         grep(1)

grep 2.21 - Generated Mon Nov 24 06:19:45 CST 2014