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grep, egrep, fgrep, zgrep, zegrep, zfgrep, bzgrep, bzegrep, bzfgrep -

 

NAME

        grep,  egrep,  fgrep, zgrep, zegrep, zfgrep, bzgrep, bzegrep, bzfgrep -
        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, two variant programs egrep and fgrep are available.  egrep
        is  the  same  as grep -E.  fgrep is the same as grep -F.  zgrep is the
        same as grep -Z.  zegrep is the same as grep -EZ.  zfgrep is  the  same
        as grep -FZ.
 

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.
 
        -C NUM, --context=NUM
               Print NUM lines of output context.  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 mes‐
               sage  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 termi‐
               nal driver interprets some of it as commands.
 
        --colour[=WHEN], --color[=WHEN]
               Surround the matching string with the marker find in  GREP_COLOR
               environment variable. WHEN may be ‘never’, ‘always’, or ‘auto’
 
        -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.
 
        -D ACTION, --devices=ACTION
               If an input file is a device, FIFO or socket, use ACTION to pro‐
               cess 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,  direc‐
               tories  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 new‐
               lines, any of which is to be matched.
 
        -P, --perl-regexp
               Interpret PATTERN as a Perl regular expression.  This option  is
               not supported in FreeBSD.
 
        -f FILE, --file=FILE
               Obtain  patterns  from  FILE, one per line.  The empty file con‐
               tains 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.
 
        -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.
 
        --label=LABEL
               Displays input actually coming from standard input as input com‐
               ing  from  file LABEL.  This is especially useful for tools like
               zgrep, e.g.  gzip -cd foo.gz |grep --label=foo something
 
        --line-buffered
               Flush output on every line.  Note that this incurs a performance
               penalty.
 
        -q, --quiet, --silent
               Quiet;  do  not write anything to standard output.  Exit immedi‐
               ately 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 equiv‐
               alent 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 con‐
               form 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-Win‐
               dows.
 
        -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 plat‐
               forms other than MS-DOS and MS-Windows.
 
        -V, --version
               Print the version number of grep to standard error.   This  ver‐
               sion 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 con‐
               stituent 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.
 
        --null Output  a  zero  byte  (the  ASCII NUL character) instead of the
               character that normally follows a file name.  For example,  grep
               -l  --null  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, --decompress
               Decompress the input data before searching.  This option is only
               available if compiled with zlib(3) library.
 
        -J, --bz2decompress
               Decompress  the bzip2(1) compressed input data before searching.
        A regular expression is a pattern that  describes  a  set  of  strings.
        Regular  expressions  are constructed analogously to arithmetic expres‐
        sions, by using various operators to combine smaller expressions.
 
        grep understands two different versions of regular  expression  syntax:
        “basic”  and “extended.”  In GNU grep, there is no difference in avail‐
        able functionality using  either  syntax.   In  other  implementations,
        basic regular expressions are less powerful.  The following description
        applies to extended regular expressions; differences for basic  regular
        expressions are summarized afterwards.
 
        The  fundamental building blocks are the regular expressions that match
        a single character.  Most characters, including all letters and digits,
        are  regular expressions that match themselves.  Any 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 charac‐
        ters 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 dictio‐
        nary  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:],  [:blank:],   [: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 oper‐
        ators:
        ?      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 subex‐
        pression.
 
        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 regu‐
        lar 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 specifica‐
        tion.  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.
        Grep’s behavior is affected by the following environment variables.
 
        A  locale  LC_foo is specified by examining the three environment vari‐
        ables LC_ALL, LC_foo, LANG, in that order.  The first  of  these  vari‐
        ables  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 --direc     
               tories=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”.
 

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.
 

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Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.