egrep(1)


NAME

   grep, egrep, fgrep, rgrep - 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, fgrep and rgrep are  the  same
   as  grep -E,  grep -F,  and  grep -r, 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 (instead of regular
          expressions), 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 the pattern as a  Perl-compatible  regular  expression
          (PCRE).   This  is  highly  experimental and grep -P may warn of
          unimplemented features.

   Matching Control
   -e PATTERN, --regexp=PATTERN
          Use PATTERN as the pattern.  If this  option  is  used  multiple
          times or is combined with the -f (--file) option, search for all
          patterns given.  This option can be used to  protect  a  pattern
          beginning with "-".

   -f FILE, --file=FILE
          Obtain patterns from FILE, one per line.  If this option is used
          multiple times or is combined with  the  -e  (--regexp)  option,
          search  for  all  patterns  given.  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.  This option has no effect if -x is also specified.

   -x, --line-regexp
          Select  only  those  matches  that exactly match the whole line.
          For a regular expression pattern, this  is  like  parenthesizing
          the pattern and then surrounding it with ^ and $.

   -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  a  file's  data  or metadata indicate that the file contains
          binary data, assume that the file is  of  type  TYPE.   Non-text
          bytes  indicate  binary data; these are either output bytes that
          are improperly encoded for the current  locale,  or  null  input
          bytes when the -z option is not given.

          By  default, TYPE is binary, and when grep discovers that a file
          is binary it suppresses any further output, and instead  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, when grep discovers  that  a  file  is
          binary it assumes that the rest of the 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.

          When  type  is  binary,  grep  may  treat non-text bytes as line
          terminators even without the -z  option.   This  means  choosing
          binary  versus text can affect whether a pattern matches a file.
          For example, when type is binary the pattern q$  might  match  q
          immediately  followed  by  a  null byte, even though this is not
          matched when type is text.  Conversely, when type is binary  the
          pattern . (period) might not match a null byte.

          Warning:  The  -a  option 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.  On the other
          hand, when reading files whose text encodings  are  unknown,  it
          can   be  helpful  to  use  -a  or  to  set  LC_ALL='C'  in  the
          environment, in order to find more matches even if  the  matches
          are unsafe for direct display.

   -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  any  command-line file with a name suffix that matches the
          pattern GLOB, using wildcard matching; a name suffix  is  either
          the  whole  name,  or any suffix starting after a / and before a
          +non-/.  When searching recursively, skip any subfile whose base
          name  matches  GLOB; the base name is the part after the last /.
          A pattern 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=GLOB
          Skip  any command-line directory with a name suffix that matches
          the  pattern  GLOB.   When  searching  recursively,   skip   any
          subdirectory whose base name matches GLOB.  Ignore any redundant
          trailing slashes in GLOB.

   -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.  Note that
          if  no  file  operand  is  given,  grep  searches  the   working
          directory.  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 whether  a  file  is  text  or  binary  as
          described  for  the  --binary-files option.  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  input  and  output  data  as  sequences  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"  (BRE), "extended" (ERE) and "perl" (PCRE).  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-compatible  regular  expressions   give   additional
   functionality,  and are documented in pcresyntax(3) and pcrepattern(3),
   but work only if PCRE is available in the 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 	 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).  The shell command locale -a lists locales that
   are currently available.

   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.  This category  also  determines  the  character
          encoding,  that  is, whether text is encoded in UTF-8, ASCII, or
          some other encoding.  In the C or POSIX locale,  all  characters
          are  encoded  as  a  single  byte  and  every  byte  is  a valid
          character.

   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, 2005-2016 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),
   xargs(1),  zgrep(1),  read(2),  pcre(3), pcresyntax(3), pcrepattern(3),
   terminfo(5), glob(7), regex(7).

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

   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.





Opportunity


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