# man > ACK(1p)

> **TLDR:** A search tool like `grep`, optimized for developers.
>
- Search for files containing a string or `regex` in the current directory recursively:
  `ack "{{search_pattern}}"`
- Search for a case-insensitive pattern:
  `ack {{-i|--ignore-case}} "{{search_pattern}}"`
- Search for lines matching a pattern, printing only the matched text and not the rest of the line:
  `ack {{-o|--output '$&'}} "{{search_pattern}}"`
- Limit search to files of a specific type:
  `ack {{-t|--type}} {{ruby}} "{{search_pattern}}"`
- Do not search in files of a specific type:
  `ack {{-t|--type}} no{{ruby}} "{{search_pattern}}"`
- Count the total number of matches found:
  `ack {{-c|--count}} {{-h|--no-filename}} "{{search_pattern}}"`
- Print the file names and the number of matches for each file only:
  `ack {{-c|--count}} {{-l|--files-with-matches}} "{{search_pattern}}"`
- List all the values that can be used with `--type`:
  `ack --help-types`

*Source: tldr-pages*

---

[_ACK_(1p)](https://www.chedong.com/phpMan.php/man/ACK/1p/markdown)                          User Contributed Perl Documentation                         [_ACK_(1p)](https://www.chedong.com/phpMan.php/man/ACK/1p/markdown)

## NAME
       ack - grep-like text finder

## SYNOPSIS
           ack [options] PATTERN [FILE...]
           ack -f [options] [DIRECTORY...]

## DESCRIPTION
       ack is designed as an alternative to _grep_ for programmers.

       ack searches the named input FILEs or DIRECTORYs for lines containing a match to the given
       PATTERN.  By default, ack prints the matching lines.  If no FILE or DIRECTORY is given, the
       current directory will be searched.

       PATTERN is a Perl regular expression.  Perl regular expressions are commonly found in other
       programming languages, but for the particulars of their behavior, please consult perlreref
       <<https://perldoc.perl.org/perlreref.html>>.  If you don't know how to use regular expression
       but are interested in learning, you may consult perlretut
       <<https://perldoc.perl.org/perlretut.html>>.  If you do not need or want ack to use regular
       expressions, please see the "-Q"/"--literal" option.

       Ack can also list files that would be searched, without actually searching them, to let you
       take advantage of ack's file-type filtering capabilities.

## FILE SELECTION
       If files are not specified for searching, either on the command line or piped in with the
       "-x" option, _ack_ delves into subdirectories selecting files for searching.

       _ack_ is intelligent about the files it searches.  It knows about certain file types, based on
       both the extension on the file and, in some cases, the contents of the file.  These
       selections can be made with the **--type **option.

       With no file selection, _ack_ searches through regular files that are not explicitly excluded
       by **--ignore-dir **and **--ignore-file **options, either present in _ackrc_ files or on the command
       line.

       The default options for _ack_ ignore certain files and directories.  These include:

       •   Backup files: Files matching _#*#_ or ending with _~_.

       •   Coredumps: Files matching _core.\d+_

       •   Version control directories like _.svn_ and _.git_.

       Run _ack_ with the "--dump" option to see what settings are set.

       However,  _ack_  always  searches the files given on the command line, no matter what type.  If
       you tell _ack_ to search in a coredump, it will search in a coredump.

## DIRECTORY SELECTION
       _ack_ descends through the directory  tree  of  the  starting  directories  specified.   If  no
       directories  are  specified,  the current working directory is used.  However, it will ignore
       the shadow directories used by many version control systems, and the build  directories  used
       by  the  Perl  MakeMaker  system.   You may add or remove a directory from this list with the
       **--[no]ignore-dir **option. The option may be repeated to add/remove multiple  directories  from
       the ignore list.

       For a complete list of directories that do not get searched, run "ack --dump".

## MATCHING IN A RANGE OF LINES
       The  "--range-start"  and  "--range-end"  options  let  you specify ranges of lines to search
       within each file.

       Say you had the following file, called _testfile_:

           # This function calls print on "foo".
           sub foo {
               print 'foo';
           }
           my $print = 1;
           sub bar {
               print 'bar';
           }
           my $task = 'print';

       Calling "ack print" will give us five matches:

           $ ack print testfile
           # This function calls print on "foo".
               print 'foo';
           my $print = 1;
               print 'bar';
           my $task = 'print';

       What if we only want to search for "print" within the subroutines?  We can specify ranges  of
       lines  that  we  want ack to search.  The range starts with any line that matches the pattern
       "^sub \w+", and stops with any line that matches "^}".

           $ ack --range-start='^sub \w+' --range-end='^}' print testfile
               print 'foo';
               print 'bar';

       Note that ack searched two ranges of lines.  The listing below shows which lines  were  in  a
       range and which were out of the range.

           Out # This function calls print on "foo".
           In  sub foo {
           In      print 'foo';
           In  }
           Out my $print = 1;
           In  sub bar {
           In      print 'bar';
           In  }
           Out my $task = 'print';

       You  don't  have  to  specify  both "--range-start" and "--range-end".  IF "--range-start" is
       omitted, then the range runs from the first line in  the  file  until  the  first  line  that
       matches "--range-end".  Similarly, if "--range-end" is omitted, the range runs from the first
       line matching "--range-start" to the end of the file.

       For  example,  if  you  wanted  to  search  all HTML files up until the first instance of the
       "<body>", you could do

           ack foo --html --range-end='<body>'

       Or to search after Perl's `__DATA__` or `__END__` markers, you would do

           ack pattern --perl --range-start='^__(END|DATA)__'

       It's possible for a range to start and stop on the same line.  For example

           --range-start='<title>' --range-end='</title>'

       would match this line as both the start and end of the range, making a one-line range.

           <title>Page title</title>

       Note that the patterns in "--range-start" and "--range-end" are not affected by options  like
       "-i", "-w" and "-Q" that modify the behavior of the main pattern being matched.

       Again,  ranges  only  affect  where matches are looked for.  Everything else in ack works the
       same way.  Using "-c" option with a range will give a count of all the  matches  that  appear
       within  those  ranges.   The "-l" shows those files that have a match within a range, and the
       "-L" option shows files that do not have a match within a range.

       The "-v" option for negating a match works inside the range, too.  To see  lines  that  don't
       match "google" within the "<head>" section of your HTML files, you could do:

           ack google -v --html --range-start='<head' --range-end='</head>'

       Specifying  a  range  to search does not affect how matches are displayed.  The context for a
       match will still be the same, and

       Using the context options work the same way, and will show context lines for matches even  if
       the context lines fall outside the range.  Similarly, "--passthru" will show all lines in the
       file, but only show matches for lines within the range.

## OPTIONS
### --ackrc
           Specifies an ackrc file to load after all others; see "ACKRC LOCATION SEMANTICS".

### -A _NUM_ --after-context=NUM
           Print _NUM_ lines of trailing context after matching lines.

### -B _NUM_ --before-context=NUM
           Print _NUM_ lines of leading context before matching lines.

### --[no]break
           Print   a   break  between  results  from  different  files.  On  by  default  when  used
           interactively.

### -C [_NUM_] --context[=_NUM_]
           Print _NUM_ lines (default 2) of context around matching lines.  You can specify zero lines
           of context to override another context specified in an ackrc.

### -c --count
           Suppress normal output; instead print a count of matching lines for each input file.   If
           **-l  **is  in  effect,  it  will  only show the number of lines for each file that has lines
           matching.  Without **-l**, some line counts may be zeroes.

           If combined with **-h **(**--no-filename**) ack outputs only one total count.

       **--[no]color**, **--[no]colour**
           **--color **highlights the matching text.  **--nocolor **suppresses the color.   This  is  on  by
           default unless the output is redirected.

           On  Windows,  this  option  is  off  by default unless the [Win32::Console::ANSI](https://www.chedong.com/phpMan.php/perldoc/Win32%3A%3AConsole%3A%3AANSI/markdown) module is
           installed or the "ACK_PAGER_COLOR" environment variable is used.

### --color-filename=color
           Sets the color to be used for filenames.

### --color-match=color
           Sets the color to be used for matches.

### --color-colno=color
           Sets the color to be used for column numbers.

### --color-lineno=color
           Sets the color to be used for line numbers.

### --[no]column
           Show the column number of the first match.  This is helpful for editors  that  can  place
           your cursor at a given position.

### --create-ackrc
           Dumps  the  default  ack options to standard output.  This is useful for when you want to
           customize the defaults.

### --dump
           Writes the list of options loaded and where they came from to standard output.  Handy for
           debugging.

### --[no]env
           **--noenv **disables all environment processing.  No  _.ackrc_  is  read  and  all  environment
           variables are ignored. By default, _ack_ considers _.ackrc_ and settings in the environment.

### --flush
           **--flush  **flushes  output  immediately.   This  is  off  by  default unless ack is running
           interactively (when output goes to a pipe or file).

### -f  
           PATTERN must not be specified, or it will be taken as a path to search.

### --files-from=FILE
           The  list  of files to be searched is specified in _FILE_.  The list of files are separated
           by newlines.  If _FILE_ is "-", the list is loaded from standard input.

           Note that the list of files is **not **filtered in any way.   If  you  add  "--type=html"  in
           addition to "--files-from", the "--type" will be ignored.

### --[no]filter
           Forces ack to act as if it were receiving input via a pipe.

### --[no]follow
           Follow  or  don't follow symlinks, other than whatever starting files or directories were
           specified on the command line.

           This is off by default.

### -g PATTERN
           Print searchable files where the relative path + filename matches _PATTERN_.

           Note that

               ack -g foo

           is exactly the same as

               ack -f | ack foo

           This means that just as ack will not search, for example, _.jpg_ files, "-g" will not  list
           _.jpg_ files either.  ack is not intended to be a general-purpose file finder.

           Note  also  that if you have "-i" in your .ackrc that the filenames to be matched will be
           case-insensitive as well.

           This option can be combined with **--color **to make it easier to spot the match.

### --[no]group
           **--group **groups matches by file name.  This is the default when used interactively.

           **--nogroup **prints one result per line, like grep.  This is  the  default  when  output  is
           redirected.

### -H --with-filename
           Print  the  filename  for  each  match.  This  is  the  default unless searching a single
           explicitly specified file.

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

### --[no]heading
           Print a filename heading above each file's  results.   This  is  the  default  when  used
           interactively.

### --help
           Print a short help statement.

### --help-types
           Print all known types.

### --help-colors
           Print a chart of various color combinations.

### --help-rgb-colors
           Like **--help-colors **but with more precise RGB colors.

### -i --ignore-case
           Ignore case distinctions in PATTERN.  Overrides **--smart-case **and **-I**.

### -I --no-ignore-case
           Turns on case distinctions in PATTERN.  Overrides **--smart-case **and **-i**.

### --ignore-ack-defaults
           Tells ack to completely ignore the default definitions provided with ack.  This is useful
           in combination with **--create-ackrc **if you _really_ want to customize ack.

       **--[no]ignore-dir=_DIRNAME_**, **--[no]ignore-directory=DIRNAME**
           Ignore  directory  (as  CVS, .svn, etc are ignored). May be used multiple times to ignore
           multiple directories. For example, mason users may wish to include **--ignore-dir=data**. The
           **--noignore-dir **option allows users to search directories which would normally be  ignored
           (perhaps to research the contents of _.svn/props_ directories).

           The  _DIRNAME_  must always be a simple directory name. Nested directories like _foo/bar_ are
           NOT supported. You would need to specify **--ignore-dir=foo **and then no files from any  foo
           directory are taken into account by ack unless given explicitly on the command line.

### --ignore-file=FILTER:ARGS
           Ignore  files  matching  _FILTER:ARGS_.  The filters are specified identically to file type
           filters as seen in "Defining your own types".

### -k --known-types
           Limit selected files to those with types that ack knows about.

### -l --files-with-matches
           Only print the filenames of matching files, instead of the matching text.

### -L --files-without-matches
           Only print the filenames of files that do _NOT_ match.

### --match PATTERN
           Specify the _PATTERN_ explicitly. This is helpful if you don't want to  put  the  regex  as
           your first argument, e.g. when executing multiple searches over the same set of files.

               # search for foo and bar in given files
               ack file1 t/file* --match foo
               ack file1 t/file* --match bar

### -m=_NUM_ --max-count=NUM
           Print  only  _NUM_  matches  out  of each file.  If you want to stop ack after printing the
           first match of any kind, use the **-1 **options.

### --man
           Print this manual page.

### -n --no-recurse
           No descending into subdirectories.

### --not=PATTERN
           Specifies a _PATTERN_ that must NOT me true on a given line for  a  match  to  occur.  This
           option can be repeated.

           If  you  want to find all the lines with "dogs" but not if "cats" or "fish" appear on the
           line, use:

               ack dogs --not cats --not fish

           Note that the options that affect "dogs" also affect "cats" and "fish", so if you have

               ack -i -w dogs --not cats

           the the search for both "dogs" and "cats" will be case-insensitive and be word-limited.

### -o  
           exactly the same as "--output=$&".

### --output=expr
           Output  the  evaluation  of  _expr_ for each line (turns off text highlighting). If PATTERN
           matches more than once then a line is output for each non-overlapping match.

           _expr_ may contain the strings "\n", "\r"  and  "\t",  which  will  be  expanded  to  their
           corresponding characters line feed, carriage return and tab, respectively.

           _expr_ may also contain the following Perl special variables:

           $1 through $9
               The  subpattern from the corresponding set of capturing parentheses.  If your pattern
               is "(.+) and (.+)", and the string is "this and that', then $1 is "this"  and  $2  is
               "that".

           $_  The contents of the line in the file.

           $.  The number of the line in the file.

           $&, "$`" and "$'"
               $&  is  the  the  string matched by the pattern, "$`" is what precedes the match, and
               "$'" is what  follows  it.   If  the  pattern  is  "gra(ph|nd)"  and  the  string  is
               "lexicographic", then $& is "graph", "$`" is "lexico" and "$'" is "ic".

               Use of these variables in your output will slow down the pattern matching.

           $+  The  match made by the last parentheses that matched in the pattern.  For example, if
               your pattern is "Version: (.+)|Revision: (.+)", then $+ will contain whichever set of
               parentheses matched.

           $f  $f is available, in "--output" only, to insert the filename.  This is a stand-in  for
               the  discovered  $filename  usage  in  old  "ack2 --output", which is disallowed with
               "ack3" improved security.

               The intended usage is  to  provide  the  grep  or  compile-error  syntax  needed  for
               editor/IDE go-to-line integration, e.g. "--output=$f:$.:$_" or "--output=$f\t$.\t$&"

       **--pager=_program_**, **--nopager**
           **--pager  **directs  ack's  output  through  _program_.   This  can  also be specified via the
           "ACK_PAGER" and "ACK_PAGER_COLOR" environment variables.

           Using --pager does not suppress grouping and coloring like piping output on the  command-
           line does.

           **--nopager  **cancels  any setting in _~/.ackrc_, "ACK_PAGER" or "ACK_PAGER_COLOR".  No output
           will be sent through a pager.

### --passthru
           Prints all lines, whether or not they match  the  expression.   Highlighting  will  still
           work,  though, so it can be used to highlight matches while still seeing the entire file,
           as in:

               # Watch a log file, and highlight a certain IP address.
               $ tail -f ~/access.log | ack --passthru 123.45.67.89

### --print0
           Only works in conjunction with **-f**, **-g**, **-l **or **-c**, options that only list  filenames.   The
           filenames  are  output  separated  with a null byte instead of the usual newline. This is
           helpful when dealing with filenames that contain whitespace, e.g.

               # Remove all files of type HTML.
               ack -f --html --print0 | xargs -0 rm -f

### -p[N] --proximate[=N]
           Groups together match lines that are within N lines of each other.  This  is  useful  for
           visually picking out matches that appear close to other matches.

           For example, if you got these results without the "--proximate" option,

               15: First match
               18: Second match
               19: Third match
               37: Fourth match

           they would look like this with "--proximate=1"

               15: First match

               18: Second match
               19: Third match

               37: Fourth match

           and this with "--proximate=3".

               15: First match
               18: Second match
               19: Third match

               37: Fourth match

           If N is omitted, N is set to 1.

### -P   --proximate  --proximate=0

### -Q --literal
           Quote all metacharacters in PATTERN, it is treated as a literal.

### -r -R --recurse
           Recurse  into  sub-directories.  This is the default and just here for compatibility with
           grep. You can also use it for turning **--no-recurse **off.

       **--range-start=PATTERN**, **--range-end=PATTERN**
           Specifies patterns that mark the start and end of a range.  See "MATCHING IN A  RANGE  OF
           LINES" for details.

### -s  

### -S --[no]smart-case --no-smart-case
           Ignore  case  in  the search strings if PATTERN contains no uppercase characters. This is
           similar to "smartcase" in the vim text editor.  The options overrides **-i **and **-I**.

           **-S **is a synonym for **--smart-case**.

           **-i **always overrides this option.

### --sort-files
           Sorts the found files lexicographically.  Use this if you want your file listings  to  be
           deterministic between runs of _ack_.

### --show-types
           Outputs the filetypes that ack associates with each file.

           Works with **-f **and **-g **options.

### -t TYPE --type=TYPE --TYPE
           Specify  the  types  of files to include in the search.  TYPE is a filetype, like _perl_ or
           _xml_.  **--type=perl **can also be specified as **--perl**, although this is deprecated.

           Type inclusions can be repeated and are ORed together.

           See _ack_ _--help-types_ for a list of valid types.

### -T TYPE --type=noTYPE --noTYPE
           Specifies the type of files to exclude from the search.  **--type=noperl  **can  be  done  as
           **--noperl**, although this is deprecated.

           If  a  file  is of both type "foo" and "bar", specifying both **--type=foo **and **--type=nobar**
           will exclude the file, because an exclusion takes precedence over an inclusion.

### --type-add _TYPE_:_FILTER_:ARGS
           Files with the given ARGS applied to the given FILTER are recognized  as  being  of  (the
           existing) type TYPE.  See also "Defining your own types".

### --type-set _TYPE_:_FILTER_:ARGS
           Files  with  the  given  ARGS applied to the given FILTER are recognized as being of type
           TYPE. This replaces an existing definition for type TYPE.  See also  "Defining  your  own
           types".

### --type-del TYPE
           The  filters  associated with TYPE are removed from Ack, and are no longer considered for
           searches.

### --[no]underline
           Turns on underlining of matches, where "underlining" is printing a line of  carets  under
           the match.

               $ ack -u foo
               peanuts.txt
               17: Come kick the football you fool
                                 ^^^          ^^^
               623: Price per square foot
                                     ^^^

           This  is  useful  if you're dumping the results of an ack run into a text file or printer
           that doesn't support ANSI color codes.

           The setting of underline does not affect highlighting of matches.

### -v --invert-match
           Invert match: select non-matching lines.

### --version
           Display version and copyright information.

### -w --word-regexp
           Force PATTERN to match only whole words.

### -x   --files-from=-
           input, with one line per file.

           Note  that  the  list  of  files is **not **filtered in any way.  If you add "--type=html" in
           addition to "-x", the "--type" will be ignored.

### -1   --max-count=1  
           **-m1**,  where  only  one  match per file is shown.  Also, **-1 **works with **-f **and **-g**, where **-m**
           does not.

### --thpppt
           Display the all-important Bill The Cat logo.  Note that the exact spelling of  **--thpppppt**
           is not important.  It's checked against a regular expression.

### --bar
           Check with the admiral for traps.

### --cathy
           Chocolate, Chocolate, Chocolate!

**THE .ackrc FILE**
       The  _.ackrc_  file contains command-line options that are prepended to the command line before
       processing.  Multiple options may live on multiple lines.   Lines  beginning  with  a  #  are
       ignored.  A _.ackrc_ might look like this:

           # Always sort the files
           --sort-files

           # Always color, even if piping to another program
           --color

           # Use "less -r" as my pager
           --pager=less -r

       Note that arguments with spaces in them do not need to be quoted, as they are not interpreted
       by the shell. Basically, each _line_ in the _.ackrc_ file is interpreted as one element of @ARGV.

       _ack_  looks in several locations for _.ackrc_ files; the searching process is detailed in "ACKRC
       LOCATION SEMANTICS".  These files are not considered if **--noenv **is specified on  the  command
       line.

## Defining your own types
       ack  allows  you  to  define your own types in addition to the predefined types. This is done
       with command line options that are best put into an _.ackrc_ file - then you  do  not  have  to
       define  your  types over and over again. In the following examples the options will always be
       shown on one command line so that they can be easily copy & pasted.

       File types can be specified both with the the _--type=xxx_ option,  or  the  file  type  as  an
       option  itself.   For  example,  if  you  create  a  filetype  of  "cobol",  you  can specify
       _--type=cobol_ or simply _--cobol_.  File types must be at least two characters  long.   This  is
       why the C language is _--cc_ and the R language is _--rr_.

       _ack_  _--perl_  _foo_  searches  for  foo in all perl files. _ack_ _--help-types_ tells you, that perl
       files are files ending in .pl, .pm, .pod or .t. So what if you  would  like  to  include  .xs
       files  as  well  when  searching for --perl files? _ack_ _--type-add_ _perl:ext:xs_ _--perl_ _foo_ does
       this for you. **--type-add **appends additional extensions to an existing type.

       If you want to define a  new  type,  or  completely  redefine  an  existing  type,  then  use
       **--type-set**.  _ack_ _--type-set_ _eiffel:ext:e,eiffel_ defines the type _eiffel_ to include files with
       the extensions .e or .eiffel. So to search for all eiffel files containing the word  Bertrand
       use  _ack_  _--type-set_  _eiffel:ext:e,eiffel_  _--eiffel_  _Bertrand_.   As usual, you can also write
       **--type=eiffel **instead of **--eiffel**. Negation also works, so  **--noeiffel  **excludes  all  eiffel
       files from a search. Redefining also works: _ack_ _--type-set_ _cc:ext:c,h_ and _.xs_ files no longer
       belong to the type _cc_.

       When defining your own types in the _.ackrc_ file you have to use the following:

         --type-set=eiffel:ext:e,eiffel

       or writing on separate lines

         --type-set
         eiffel:ext:e,eiffel

       The following does **NOT **work in the _.ackrc_ file:

         --type-set eiffel:ext:e,eiffel

       In  order  to  see  all  currently  defined  types,  use  _--help-types_,  e.g.  _ack_ _--type-set_
       _backup:ext:bak_ _--type-add_ _perl:ext:perl_ _--help-types_

       In addition to filtering based on extension, ack offers additional filter types.  The generic
       syntax is _--type-set_ _TYPE:FILTER:ARGS_; _ARGS_ depends on the value of _FILTER_.

       is:_FILENAME_
           _is_ filters match the target filename exactly.  It takes exactly one  argument,  which  is
           the name of the file to match.

           Example:

               --type-set make:is:Makefile

       ext:_EXTENSION_[,_EXTENSION2_[,...]]
           _ext_  filters  match  the  extension  of the target file against a list of extensions.  No
           leading dot is needed for the extensions.

           Example:

               --type-set perl:ext:pl,pm,t

       match:_PATTERN_
           _match_ filters match the target  filename  against  a  regular  expression.   The  regular
           expression is made case-insensitive for the search.

           Example:

               --type-set make:match:/(gnu)?makefile/

       firstlinematch:_PATTERN_
           _firstlinematch_  matches  the  first line of the target file against a regular expression.
           Like _match_, the regular expression is made case insensitive.

           Example:

               --type-add perl:firstlinematch:/perl/

## ACK COLORS
       ack allows customization of the colors it uses when presenting matches onscreen.  It uses the
       colors available in Perl's  [Term::ANSIColor](https://www.chedong.com/phpMan.php/perldoc/Term%3A%3AANSIColor/markdown)  module,  which  provides  the  following  listed
       values. Note that case does not matter when using these values.

       There are four different colors ack uses:

           Aspect      Option              Env. variable       Default
           --------    -----------------   ------------------  ---------------
           filename    --color-filename    ACK_COLOR_FILENAME  black on_yellow
           match       --color-match       ACK_COLOR_MATCH     bold green
           line no.    --color-lineno      ACK_COLOR_LINENO    bold yellow
           column no.  --color-colno       ACK_COLOR_COLNO     bold yellow

       The  column  number column is only used if the column number is shown because of the --column
       option.

       Colors  may  be  specified  by  command-line  option,  such  as  "ack   --color-filename='red
       on_white'",   or  by  setting  an  environment  variable,  such  as  "ACK_COLOR_FILENAME='red
       on_white'".  Options for colors can be set in your ACKRC file (See "THE .ackrc FILE").

       ack can understand the following colors for the foreground:

           black red green yellow blue magenta cyan white

       The optional background color is specified by prepending  "on_"  to  one  of  the  foreground
       colors:

           on_black on_red on_green on_yellow on_blue on_magenta on_cyan on_white

       Each of the foreground colors can be modified with the following attributes, which may or may
       not be supported by your terminal:

           bold faint italic underline blink reverse concealed

       Any combinations of modifiers can be added to the foreground color. If your terminal supports
       it, and you enjoy visual punishment, you can specify:

           ack --color-filename="blink italic underline bold red on_yellow"

       For  charts  of  the  colors  and  what  they  look  like,  run  "ack --help-colors" and "ack
       --help-rgb-colors".

       If the eight standard colors, in their bold, faint and unmodified states, aren't  enough  for
       you  to  choose from, you can also specify colors by their RGB values.  They are specified as
       "rgbXYZ" where X, Y, and Z are values between 0 and 5 giving the intensity of red, green  and
       blue, respectively.  Therefore, "rgb500" is pure red, "rgb505" is purple, and so on.

       Background  colors  can be specified with the "on_" prefix prepended on an RGB color, so that
       "on_rgb505" would be a purple background.

       The modifier attributes of blink, italic, underscore and so on may or may not work on the RGB
       colors.

       For a chart of the 216 possible RGB colors, run "ack --help-rgb-colors".

## ENVIRONMENT VARIABLES
       For commonly-used ack options, environment  variables  can  make  life  much  easier.   These
       variables are ignored if **--noenv **is specified on the command line.

       ACKRC
           Specifies  the location of the user's _.ackrc_ file.  If this file doesn't exist, _ack_ looks
           in the default location.

       ACK_COLOR_COLNO
           Color specification for the column number in ack's output.  By default, the column number
           is not shown.  You have to enable it with the **--column  **option.   See  the  section  "ack
           Colors" above.

       ACK_COLOR_FILENAME
           Color  specification  for  the  filename  in  ack's output.  See the section "ack Colors"
           above.

       ACK_COLOR_LINENO
           Color specification for the line number in ack's output.  See the  section  "ack  Colors"
           above.

       ACK_COLOR_MATCH
           Color  specification  for the matched text in ack's output.  See the section "ack Colors"
           above.

       ACK_PAGER
           Specifies a pager program, such as "more", "less" or "most", to which ack will  send  its
           output.

           Using  "ACK_PAGER"  does  not  suppress  grouping  and coloring like piping output on the
           command-line does, except that on Windows ack  will  assume  that  "ACK_PAGER"  does  not
           support color.

           "ACK_PAGER_COLOR" overrides "ACK_PAGER" if both are specified.

       ACK_PAGER_COLOR
           Specifies a pager program that understands ANSI color sequences.  Using "ACK_PAGER_COLOR"
           does not suppress grouping and coloring like piping output on the command-line does.

           If you are not on Windows, you never need to use "ACK_PAGER_COLOR".

**ACK & OTHER TOOLS**
### Simple vim integration
       _ack_ integrates easily with the Vim text editor. Set this in your _.vimrc_ to use _ack_ instead of
       _grep_:

           set grepprg=ack\ -k

       That example uses "-k" to search through only files of the types ack knows about, but you may
       use  other  default flags. Now you can search with _ack_ and easily step through the results in
       Vim:

         :grep Dumper perllib

### Editor integration
       Many users have integrated ack into their preferred text editors.  For details and links, see
       <<https://beyondgrep.com/more-tools/>>.

### Shell and Return Code
       For greater compatibility with _grep_, _ack_ in normal use returns shell return or exit code of 0
       only if something is found and 1 if no match is found.

       (Shell exit code 1 is "$?=256" in perl with "system" or backticks.)

       The _grep_ code 2 for errors is not used.

       If "-f" or "-g" are specified, then 0 is returned if at least one file is found.  If no files
       are found, then 1 is returned.

## DEBUGGING ACK PROBLEMS
       If ack gives you output you're not expecting, start with a few simple steps.

### Try it with --noenv
       Your environment variables and _.ackrc_ may be doing things you're not expecting, or  forgotten
       you specified.  Use **--noenv **to ignore your environment and _.ackrc_.

### Use -f to see what files have been selected for searching
       Ack's  **-f  **was originally added as a debugging tool.  If ack is not finding matches you think
       it should find, run _ack_ _-f_ to see what files have  been  selected.   You  can  also  add  the
       "--show-types" options to show the type of each file selected.

### Use --dump
       This  lists  the  ackrc  files  that are loaded and the options loaded from them.  You may be
       loading an _.ackrc_ file that you didn't know you were loading.

## ACKRC LOCATION SEMANTICS
       Ack can load its configuration from many sources.  The following list specifies  the  sources
       Ack  looks  for  configuration files; each one that is found is loaded in the order specified
       here, and each one overrides options set in any of the sources preceding it.   (For  example,
       if  I  set --sort-files in my user ackrc, and --nosort-files on the command line, the command
       line takes precedence)

       •   Defaults  are  loaded  from  [App::Ack::ConfigDefaults](https://www.chedong.com/phpMan.php/perldoc/App%3A%3AAck%3A%3AConfigDefaults/markdown).   This  can   be   omitted   using
           "--ignore-ack-defaults".

       •   Global ackrc

           Options  are then loaded from the global ackrc.  This is located at "/etc/ackrc" on Unix-
           like systems.

           Under Windows XP and earlier, the global  ackrc  is  at  "C:\Documents  and  Settings\All
           Users\Application Data\ackrc"

           Under Windows Vista/7, the global ackrc is at "C:\ProgramData\ackrc"

           The "--noenv" option prevents all ackrc files from being loaded.

       •   User ackrc

           Options  are  then  loaded  from  the user's ackrc.  This is located at "$HOME/.ackrc" on
           Unix-like systems.

           Under  Windows  XP  and   earlier,   the   user's   ackrc   is   at   "C:\Documents   and
           Settings\$USER\Application Data\ackrc".

           Under Windows Vista/7, the user's ackrc is at "C:\Users\$USER\AppData\Roaming\ackrc".

           If  you  want  to  load a different user-level ackrc, it may be specified with the $ACKRC
           environment variable.

           The "--noenv" option prevents all ackrc files from being loaded.

       •   Project ackrc

           Options are then loaded from the project ackrc.  The project ackrc  is  the  first  ackrc
           file  with  the name ".ackrc" or "_ackrc", first searching in the current directory, then
           the parent directory, then the grandparent directory, etc.  This  can  be  omitted  using
           "--noenv".

       •   --ackrc

           The  "--ackrc"  option  may be included on the command line to specify an ackrc file that
           can override all others.  It is consulted even if "--noenv" is present.

       •   Command line

           Options are then loaded from the command line.

**BUGS & ENHANCEMENTS**
       ack is based at GitHub at <<https://github.com/beyondgrep/ack3>>

       Please  report  any  bugs   or   feature   requests   to   the   issues   list   at   GitHub:
       <<https://github.com/beyondgrep/ack3/issues>>.

       Please  include  the  operating  system  that  you're  using;  the output of the command "ack
       --version"; and any customizations in your _.ackrc_ you may have.

       To       suggest       enhancements,       please       submit       an       issue        at
       <<https://github.com/beyondgrep/ack3/issues>>.   Also  read  the  _DEVELOPERS.md_ file in the ack
       code repository.

       Also,   feel   free   to   discuss   your   issues   on   the    ack    mailing    list    at
       <<https://groups.google.com/group/ack-users>>.

## SUPPORT
       Support for and information about _ack_ can be found at:

       •   The ack homepage

           <<https://beyondgrep.com/>>

       •   Source repository

           <<https://github.com/beyondgrep/ack3>>

       •   The ack issues list at GitHub

           <<https://github.com/beyondgrep/ack3/issues>>

       •   The ack announcements mailing list

           <<https://groups.google.com/group/ack-announcement>>

       •   The ack users' mailing list

           <<https://groups.google.com/group/ack-users>>

       •   The ack development mailing list

           <<https://groups.google.com/group/ack-users>>

## COMMUNITY
       There    are    ack    mailing    lists    and    a    Slack    channel    for    ack.    See
       <<https://beyondgrep.com/community/>> for details.

## FAQ
       This is the Frequently Asked Questions list for ack.

### Can I stop using grep now?
       Many people find _ack_ to be better than _grep_ as an everyday tool 99% of the  time,  but  don't
       throw  _grep_  away,  because  there are times you'll still need it.  For example, you might be
       looking through huge log files and not using regular expressions.  In that  case,  _grep_  will
       probably perform better.

### Why isn't ack finding a match in (some file)?
       First,  take  a  look and see if ack is even looking at the file.  ack is intelligent in what
       files it will search and which ones it won't, but sometimes that can be surprising.

       Use the "-f" switch, with no regex, to see a list of files that ack will search for you.   If
       your  file  doesn't show up in the list of files that "ack -f" shows, then ack never looks in
       it.

### Wouldn't it be great if _ack_ did search & replace?
       No, ack will always be read-only.  Perl has a perfectly good way to do search  &  replace  in
       files, using the "-i", "-p" and "-n" switches.

       You  can  certainly use ack to select your files to update.  For example, to change all "foo"
       to "bar" in all PHP files, you can do this from the Unix shell:

           $ perl -i -p -e's/foo/bar/g' $(ack -f --php)

### Can I make ack recognize _.xyz_ files?
       Yes!  Please see "Defining your own types" in the ack manual.

### Will you make ack recognize _.xyz_ files by default?
       We might, depending on how widely-used the file format is.

       Submit an issue at in the GitHub issue queue at  <<https://github.com/beyondgrep/ack3/issues>>.
       Explain  what the file format is, where we can find out more about it, and what you have been
       using in your _.ackrc_ to support it.

       Please do not bother creating a pull request.  The code for filetypes is trivial compared  to
       the rest of the process we go through.

### Why is it called ack if it's called ack-grep?
       The  name  of  the  program is "ack".  Some packagers have called it "ack-grep" when creating
       packages because there's already a package out there called "ack" that has nothing to do with
       this ack.

       I suggest you make a symlink named _ack_ that points to _ack-grep_ because  one  of  the  crucial
       benefits of ack is having a name that's so short and simple to type.

       To do that, run this with _sudo_ or as root:

          ln -s /usr/bin/ack-grep /usr/bin/ack

       Alternatively, you could use a shell alias:

           # bash/zsh
           alias ack=ack-grep

           # csh
           alias ack ack-grep

### What does _ack_ mean?
       Nothing.   I  wanted  a  name  that was easy to type and that you could pronounce as a single
       syllable.

### Can I do multi-line regexes?
       No, ack does not support regexes that match multiple lines.  Doing so would  require  reading
       in the entire file at a time.

       If  you  want  to  see  lines  near  your  match, use the "--A", "--B" and "--C" switches for
       displaying context.

### Why is ack telling me I have an invalid option when searching for "+foo"?
       ack treats command line options beginning with "+" or "-" as options; if you  would  like  to
       search  for  these,  you  may  prefix your search term with "--" or use the "--match" option.
       (However, don't forget that "+" is a regular expression metacharacter!)

### Why does "ack '.{40000,}'" fail?  Isn't that a valid regex?
       The Perl language limits the repetition quantifier to 32K.  You can search for ".{32767}" but
       not ".{32768}".

### Ack does "X" and shouldn't, should it?
       We try to remain as close to grep's behavior as possible, so when in  doubt,  see  what  grep
       does!  If there's a mismatch in functionality there, please submit an issue to GitHub, and/or
       bring it up on the ack-users mailing list.

## ACKNOWLEDGEMENTS
       How appropriate to have _ack_nowledgements!

       Thanks  to  everyone  who has contributed to ack in any way, including Thomas Gossler, Kieran
       Mace, Volker Glave, Axel  Beckert,  Eric  Pement,  Gabor  Szabo,  Frieder  Bluemle,  Grzegorz
       Kaczmarczyk,  Dan  Book,  Tomasz  Konojacki,  Salomon  Smeke, M. Scott Ford, Anders Eriksson,
       H.Merijn Brand, Duke Leto, Gerhard Poul, Ethan Mallove, Marek Kubica, Ray  Donnelly,  Nikolaj
       Schumacher,  Ed  Avis,  Nick Morrott, Austin Chamberlin, Varadinsky, Sébastien Feugère, Jakub
       Wilk, Pete Houston, Stephen Thirlwall, Jonah Bishop, Chris Rebert, Denis Howe,  Raúl  Gundín,
       James  McCoy,  Daniel  Perrett,  Steven  Lee,  Jonathan Perret, Fraser Tweedale, Raál Gundán,
       Steffen Jaeckel, Stephan Hohe, Michael Beijen, Alexandr  Ciornii,  Christian  Walde,  Charles
       Lee,  Joe  McMahon,  John  Warwick,  David  Steinbrunner, Kara Martens, Volodymyr Medvid, Ron
       Savage, Konrad Borowski, Dale Sedivic, Michael McClimon, Andrew Black, Ralph Bodenner,  Shaun
       Patterson,  Ryan  Olson,  Shlomi  Fish,  Karen Etheridge, Olivier Mengue, Matthew Wild, Scott
       Kyle, Nick Hooey, Bo Borgerson, Mark Szymanski, Marq Schneider, Packy  Anderson,  JR  Boyens,
       Dan  Sully,  Ryan Niebur, Kent Fredric, Mike Morearty, Ingmar Vanhassel, Eric Van Dewoestine,
       Sitaram Chamarty, Adam James, Richard  Carlsson,  Pedro  Melo,  AJ  Schuster,  Phil  Jackson,
       Michael  Schwern,  Jan  Dubois,  Christopher  J.  Madsen, Matthew Wickline, David Dyck, Jason
       Porritt, Jjgod Jiang, Thomas Klausner, Uri Guttman, Peter Lewis, Kevin Riggle, Ori  Avtalion,
       Torsten  Blix,  Nigel  Metheringham, Gábor Szabó, Tod Hagan, Michael Hendricks, Ævar Arnfjörð
       Bjarmason, Piers Cawley, Stephen  Steneker,  Elias  Lutfallah,  Mark  Leighton  Fisher,  Matt
       Diephouse,  Christian  Jaeger,  Bill  Sully,  Bill Ricker, David Golden, Nilson Santos F. Jr,
       Elliot Shank, Merijn Broeren, Uwe Voelker, Rick Scott, Ask  Bjørn  Hansen,  Jerry  Gay,  Will
       Coleda, Mike O'Regan, Slaven Rezić, Mark Stosberg, David Alan Pisoni, Adriano Ferreira, James
       Keenan, Leland Johnson, Ricardo Signes, Pete Krawczyk and Rob Hoelz.

## AUTHOR
       Andy Lester, "<andy at petdance.com>"

**COPYRIGHT & LICENSE**
       Copyright 2005-2023 Andy Lester.

       This  program  is  free software; you can redistribute it and/or modify it under the terms of
       the Artistic License v2.0.

       See <https://www.perlfoundation.org/artistic-license-20.html> or the LICENSE.md file that comes
       with the ack distribution.

perl v5.36.0                                 2023-06-14                                      [_ACK_(1p)](https://www.chedong.com/phpMan.php/man/ACK/1p/markdown)