ACK(1p)

📦

version 3.8.1 · 4 versions

3.8.1 · debian trixie, ubuntu resolute, ubuntu stonking (latest)
3.5.0 · ubuntu jammy
3.6.0 · debian bookworm
3.7.0 · ubuntu noble

, in debian trixie, ubuntu resolute, ubuntu stonking

💖 ACK(1p) — the Perl doc page, but make it cute 💖

okay bestie, gather round, because this is ACK(1p) from the User Contributed Perl Documentation section, and it's about to become your new fave command. no cap. 🦋

✨ NAME ✨

ack — a grep-like text finder. that's it, that's the whole vibe. 💅

🌸 SYNOPSIS 🌸

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

💜 DESCRIPTION 💜

so like, ack is literally designed to be the alternative to grep for programmers. that's the whole point of her existence. 👑

ack searches the named input FILEs or DIRECTORYs for lines containing a match to the given PATTERN. by default, ack prints the matching lines. and if you don't give her any FILE or DIRECTORY at all? she just searches the current directory. lowkey generous of her.

PATTERN is a Perl regular expression. Perl regexes are like, everywhere in other programming languages too, but for the ✨particulars✨ of their behavior, please consult perlreref <https://perldoc.perl.org/perlreref.html>. and if you don't know how to use a regular expression but you're interested in learning (periodt, we love a learner), you may consult perltut — sorry, perlretut <https://perldoc.perl.org/perlretut.html>. and if you do not need or want ack to use regular expressions? no worries bestie, check the -Q/--literal option. 🫶

ack can also just list the files that would be searched, without actually searching them, so you can take full advantage of ack's file-type filtering capabilities. she's multitalented like that.

🎀 FILE SELECTION 🎀

if files aren't specified for searching — whether that's on the command line or piped in with the -x option — ack delves into subdirectories, selecting files for searching. she goes digging. 🧚

ack is intelligent about the files she searches. she 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, whether those are 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 — and this is the important part — ack always searches the files given on the command line, no matter what type. if you tell ack to search in a coredump, she will search in a coredump. she doesn't argue. she just does it. 💀

🌈 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, she 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. and the option may be repeated to add/remove multiple directories from the ignore list. so flexible. so iconic.

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. this is the good stuff, bestie. 🔥

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';

but 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. they do their own thing. independent queens. 👑

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".
--and=PATTERN — specifies a PATTERN that MUST ALSO be found on a given line for a match to occur. this option can be repeated. 🔁

if you want to find all the lines with both dogs or cats, use:

ack dogs --and cats

note that the options that affect dogs also affect cats, so if you have

ack -i -w dogs --and cats

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

see also the other two boolean options --or and --not, neither of which can be used with --and.

-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 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 — only print the files that would be searched, without actually doing any searching. 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.

more parts incoming, bestie — don't go anywhere 💜

-h, --no-filename — bestie, when ack searches a bunch of files it loves to slap the filename in front of everything. This shuts that off. 💅
--[no]heading — prints a lil filename heading on top of each file's results. That's the default when you're using it interactively, iykyk. ✨
--help — prints a short help statement.
--help-types — prints all known types. every single one, we love a complete list.
--help-colors — prints a chart of various color combinations. it's giving aesthetic. 🌈
--help-rgb-colors — literally like --help-colors but with more precise RGB colors.
-i, --ignore-case — ignore case distinctions in PATTERN. It overrides --smart-case and -I. no cap.
-I, --no-ignore-case — turns case distinctions back ON 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. main character energy fr.
--[no]ignore-dir=DIRNAME, --[no]ignore-directory=DIRNAME — ignore a 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, go off detective 🕵️).

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. only the certified ones. 👑
-l, --files-with-matches — only print the filenames of matching files, instead of the matching text. the receipts, not the tea. 🍓
-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. (hi, you're literally reading it rn 💖)
-n, --no-recurse — no descending into subdirectories. we stay on this level, bestie.
--not=PATTERN — specifies a PATTERN that must NOT be 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

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

See also the other two boolean options --and and --or, neither of which can be used with --not. 💀

-o — show only the part of each line matching PATTERN (turns off text highlighting). This is exactly the same as --output=$&.
--or=PATTERN — specifies a PATTERN that MAY be found on a given line for a match to occur. This option can be repeated.

If you want to find all the lines with "dogs" or "cats", use:

    ack dogs --or cats

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

    ack -i -w dogs --or cats

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

See also the other two boolean options --and and --not, neither of which can be used with --or.

--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 `"$'"`

$& is the string matched by the pattern, "$`" 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 — negates the effect of the --proximate option. Shortcut for --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 — suppress error messages about nonexistent or unreadable files. This is taken from fgrep.
-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. bye bestie 👋
--[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. plot twist. 🔥
--version — display version and copyright information.
-w, --word-regexp — forces PATTERN to only match whole words, bestie. No sneaky partial hits. 💅
-x — this one's just an abbreviation for --files-from=-. Like, the list of files to search gets read from standard input, one line per file. 📋

Heads up though: that file list is not filtered in any way. So if you go adding --type=html next to -x? The --type is just gonna be ignored. Poof. Gone. 🙈

-1 — stops after reporting the first match of any kind. And no, it's not the same as --max-count=1 or -m1, because those only show one match per file. Also -1 works with -f and -g, and -m does not. Different vibes entirely. ⭐
--thpppt — displays the all-important Bill The Cat logo. 👑 And ngl, the exact spelling of --thpppppt is not important, because it's checked against a regular expression.
--bar — checks with the admiral for traps.
--cathy — Chocolate, Chocolate, Chocolate!

🎀 THE .ackrc FILE 🎀

So the .ackrc file is where you stash command-line options, and they get prepended to the command line before anything gets processed. Multiple options can live on multiple lines. Any line starting with # gets 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

Now here's the cute part — arguments with spaces in them do not need to be quoted, because they're not being 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, and that whole searching process is detailed in "ACKRC LOCATION SEMANTICS". And listen — these files are not considered at all if --noenv is specified on the command line. Periodt.

Defining your own types

ack lets you define your own types in addition to the predefined ones, which is such a serve. You do it with command line options that are best put into an .ackrc file — that way you don't have to redefine 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 --type=xxx option, or the file type as an option itself. So 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 — which is exactly why the C language is --cc and the R language is --rr. 💀

ack --perl foo searches for foo in all perl files. And ack --help-types tells you that perl files are files ending in .pl, .pm, .pod or .t. So what if you wanna include .xs files too when searching for --perl files? ack --type-add perl:ext:xs --perl foo does that for you. --type-add appends additional extensions to an existing type. Slay. ✨

If you want to define a brand new type, or completely redefine an existing one, 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 you'd use ack --type-set eiffel:ext:e,eiffel --eiffel Bertrand. As usual, you can also write --type=eiffel instead of --eiffel. Negation works too, 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. Iconic behaviour, honestly. 🌸

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

Not me warning you twice — it's giving trap. Don't do it. 🙈

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 module, which provides the following listed values. And 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 so 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. Bestie, we've all been there.

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. Not me finding out about a rogue config... 🙈

🎀 ACKRC LOCATION SEMANTICS 🎀

okay bestie, ack is lowkey a collector of config files. The following list spells out every source Ack goes looking for configuration in; each one it finds gets loaded in the order listed here, and every source overrides the options set in anything that came before it. (Like, if I put --sort-files in my user ackrc and then --nosort-files on the command line, the command line wins. Command line is the main character, periodt.)

Defaults get loaded from App::Ack::ConfigDefaults. You can skip all of that with --ignore-ack-defaults.
Global ackrc

Options then load from the global ackrc. On Unix-like systems it lives at /etc/ackrc.

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

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

The --noenv option stops all ackrc files from loading. not one. none. 💀

User ackrc

Options then load from the user's ackrc. On Unix-like systems it lives at $HOME/.ackrc.

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

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

If you wanna load a different user-level ackrc, you can point at it with the $ACKRC environment variable.

The --noenv option stops all ackrc files from loading.

Project ackrc

Options then load from the project ackrc. The project ackrc is the first ackrc file named .ackrc or _ackrc, searching first in the current directory, then the parent directory, then the grandparent directory, and so on up the whole family tree 🌳. You can skip this with --noenv.

--ackrc

The --ackrc option can go on the command line to name an ackrc file that overrides all the others. It gets consulted even if --noenv is present. sneaky but iconic 💅

Command line

Options then load from the command line. Last word, every time. ✨

🐛 BUGS & ENHANCEMENTS 🐛

ack lives on 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 you're using, the output of the command ack --version, and any customizations in your .ackrc you may have. Receipts, bestie, we need receipts 🧾

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.

And honestly, feel free to discuss your issues on the ack mailing list at <https://groups.google.com/group/ack-users>. We don't bite 🫶

🌈 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. come hang out, it's giving wholesome 🫶

💖 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. So keep both, they're not competing, they're just different girls 💅

🍓 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 about 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. Periodt. ✋ 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. like, the code is a five-minute thing, the process is the whole saga 🫠

🍓 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. name collision, so awkward 😭

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. iconic name lore, no meaning, pure vibe ✨

🍓 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. close enough bestie 🫶

🍓 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}. 32K is the ceiling, fr fr 📏

🍓 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 acknowledgements! 🥹

Thanks to everyone who has contributed to ack in any way, including Geraint Edwards, Loren Howard, Yaroslav Halchenko, Thiago Perrotta, 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.

every single one of y'all ate 💅

🧚 AUTHOR 🧚

Andy Lester, <andy at petdance.com>

🌸 COPYRIGHT & LICENSE 🌸

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.

and that's the whole page bestie!! 🎉 this version of the ack manual page came from perl v5.40.1 and was dated 2025-03-21 (the ACK(1p) page, obviously 💖). go forth and ack something gorgeous. mwah 🫶✨

📦 where this page comes from

debian trixie: ack 3.8.1-1 · Artistic-2.0
ubuntu resolute: ack 3.8.1-1 · Artistic-2.0
ubuntu stonking: ack 3.8.1-1 · Artistic-2.0
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash on 2026-10-18: a language model's rewrite of the original, under its terms

ACK(1p)

💖 ACK(1p) — the Perl doc page, but make it cute 💖

✨ NAME ✨

🌸 SYNOPSIS 🌸

💜 DESCRIPTION 💜

🎀 FILE SELECTION 🎀

🌈 DIRECTORY SELECTION 🌈

🦋 MATCHING IN A RANGE OF LINES 🦋

💅 OPTIONS 💅

$1 through $9

$_

$.

$&, "$`" and "$'"

$+

$f

🎀 THE .ackrc FILE 🎀

Defining your own types

🌈 ACK COLORS 🌈

🧚 ENVIRONMENT VARIABLES 🧚

🔥 ACK & OTHER TOOLS 🔥

Simple vim integration

Editor integration

Shell and Return Code

💀 DEBUGGING ACK PROBLEMS 💀

Try it with --noenv

Use -f to see what files have been selected for searching

Use --dump

🎀 ACKRC LOCATION SEMANTICS 🎀

🐛 BUGS & ENHANCEMENTS 🐛

🌈 SUPPORT 🌈

🦋 COMMUNITY 🦋

💖 FAQ 💖

🍓 Can I stop using grep now?

🍓 Why isn't ack finding a match in (some file)?

🍓 Wouldn't it be great if ack did search & replace?

🍓 Can I make ack recognize .xyz files?

🍓 Will you make ack recognize .xyz files by default?

🍓 Why is it called ack if it's called ack-grep?

🍓 What does ack mean?

🍓 Can I do multi-line regexes?

🍓 Why is ack telling me I have an invalid option when searching for "+foo"?

🍓 Why does "ack '.{40000,}'" fail? Isn't that a valid regex?

🍓 Ack does "X" and shouldn't, should it?

👑 ACKNOWLEDGEMENTS 👑

🧚 AUTHOR 🧚

🌸 COPYRIGHT & LICENSE 🌸

`$1` through `$9`

`$_`

`$.`

`$&`, "$`" and `"$'"`

`$+`

`$f`