GREP(1)                                                                                                                                GREP(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 (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, three variant programs egrep, fgrep and rgrep are available.  egrep is the same as grep -E.  fgrep is the same as grep -F.
       rgrep  is  the  same  as  grep -r.   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  (PCRE,  see  below).   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 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.  (-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 three different versions of regular expression syntax: “basic” (BRE), “extended” (ERE) and “perl” (PRCE). 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.
       {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

       The  exit  status is 0 if selected lines are found, and 1 if not found.  If an error occurred the exit status is 2.  (Note: POSIX error
       handling code should check for '2' or greater.)

COPYRIGHT

       Copyright 1998-2000, 2002, 2005-2011 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  <bug-grep@gnu.org>, a mailing list whose web page is <http://lists.gnu.org/mailman/listinfo/bug-grep>.  grep's
       Savannah bug tracker is located at <http://savannah.gnu.org/bugs/?group=grep>.

   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), pcresyntax(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.
 

Hi, Guest!

This is a manual page collection for Linux and Unix-like operating system.

Features

  • Works with all browsers and mobile phones.
  • The HTML in this layout validates as XHTML 1.0 strict.

Links

Search this site