Provided by: grep_2.5.1.ds2-4_i386 bug

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 the file name - is given) 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.

OPTIONS

       -A NUM, --after-context=NUM
              Print  NUM  lines  of  trailing  context  after  matching lines.
              Places  a  line  containing  --  between  contiguous  groups  of
              matches.

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

       -B NUM, --before-context=NUM
              Print NUM  lines  of  leading  context  before  matching  lines.
              Places  a  line  containing  --  between  contiguous  groups  of
              matches.

       -b, --byte-offset
              Print the byte offset within the input file before each line  of
              output.

       --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.

       -C NUM, --context=NUM
              Print  NUM lines of output context.  Places a line containing --
              between contiguous groups of matches.

       -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.

       --colour[=WHEN], --color[=WHEN]
              Surround the matching string with the marker find in  GREP_COLOR
              environment variable. WHEN may be ‘never’, ‘always’, or ‘auto’

       -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.

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

       -e PATTERN, --regexp=PATTERN
              Use PATTERN as the pattern; useful to protect patterns beginning
              with -.

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

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

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

       -H, --with-filename
              Print the filename for each match.

       -h, --no-filename
              Suppress the prefixing of  filenames  on  output  when  multiple
              files are searched.

       --help Output a brief help message.

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

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

       -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.

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

       --line-buffered
              Use line buffering, it can be a performance penalty.

       -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.

       --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.

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

       -o, --only-matching
              Show only the part of a matching line that matches PATTERN.

       -P, --perl-regexp
              Interpret PATTERN as a Perl regular expression.

       -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.

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

         --include=PATTERN
              Recurse in directories only searching file matching PATTERN.

         --exclude=PATTERN
              Recurse in directories skip file matching PATTERN.

       -s, --no-messages
              Suppress error messages about nonexistent or  unreadable  files.
              Portability  note:  unlike  GNU  grep,  traditional grep did not
              conform to POSIX.2, because traditional grep lacked a -q  option
              and  its  -s  option  behaved  like GNU grep’s -q option.  Shell
              scripts intended to be portable to traditional grep should avoid
              both  -q and -s and should redirect output to /dev/null instead.

       -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.

       -u, --unix-byte-offsets
              Report Unix-style byte offsets.   This  switch  causes  grep  to
              report  byte  offsets  as if the file were 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.

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

       -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.

       -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.

       -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 using either of the first two 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  add  additional  functionality,   but   the
       implementation  used  here  is  undocumented and is not compatible with
       other grep implementations.

       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 metacharacter  with
       special meaning may be quoted by preceding it with a backslash.

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

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

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

       The period .  matches any single character.  The symbol \w is a synonym
       for [[:alnum:]] and \W is a synonym for [^[:alnum]].

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

       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.

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

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

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

       The backreference \n, where n is a single digit, matches the  substring
       previously  matched  by  the  nth  parenthesized  subexpression  of the
       regular expression.

       In basic regular expressions the metacharacters ?, +, {, |,  (,  and  )
       lose  their  special  meaning; instead use the backslashed versions \?,
       \+, \{, \|, \(, and \).

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

       GNU egrep 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 shell command egrep{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

       grep’s behavior is affected by the following environment variables.

       A  locale  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 Brazilian Portuguese  is
       used for the LC_MESSAGES locale.  The C locale is used if none of these
       environment variables  are  set,  or  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
              Specifies the marker for highlighting.

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

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

       LC_ALL, LC_MESSAGES, LANG
              These variables specify the LC_MESSAGES locale, 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.

DIAGNOSTICS

       Normally, exit status is 0 if selected lines are found and 1 otherwise.
       But the exit status is 2 if an error occurred, unless the -q or --quiet
       or --silent option is used and a selected line is found.

BUGS

       Email  bug  reports  to  bug-gnu-utils@gnu.org.  Be sure to include the
       word “grep” somewhere in the “Subject:” field.

       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.

       Backreferences are very slow, and may require exponential time.