ACK

Section: User Contributed Perl Documentation (1)
Updated: 2019-03-19
Index

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 directories for lines containing amatch 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 expressionsare commonly found in other programming languages, but for the particularsof their behavior, please consult<http://perldoc.perl.org/perlreref.html|perlreref>. If you don't knowhow to use regular expression but are interested in learning, you mayconsult <http://perldoc.perl.org/perlretut.html|perlretut>. If you do notneed or want ack to use regular expressions, please see the"-Q"/"--literal" option.

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

FILE SELECTION

If files are not specified for searching, either on the commandline or piped in with the "-x" option, ack delves intosubdirectories selecting files for searching.

ack is intelligent about the files it searches. It knows aboutcertain file types, based on both the extension on the file and,in some cases, the contents of the file. These selections can bemade with the --type option.

With no file selection, ack searches through regular files thatare not explicitly excluded by --ignore-dir and --ignore-fileoptions, either present in ackrc files or on the command line.

The default options for ack ignore certain files and directories. Theseinclude:

•: 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 directoriesspecified. If no directories are specified, the current working directory isused. However, it will ignore the shadow directories used bymany version control systems, and the build directories used by thePerl MakeMaker system. You may add or remove a directory from thislist with the --[no]ignore-dir option. The option may be repeatedto add/remove multiple directories from the ignore list.

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

WHEN TO USE GREP

ack trumps grep as an everyday tool 99% of the time, but don'tthrow grep away, because there are times you'll still need it.

E.g., searching through huge files looking for regexes that can beexpressed with grep syntax should be quicker with grep.

If your script or parent program uses grep "--quiet" or "--silent"or needs exit 2 on IO error, use grep.

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 defaultwhen 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 contextspecified in an ackrc.

-c, --count

Suppress normal output; instead print a count of matching lines foreach input file. If -l is in effect, it will only show thenumber 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 totalcount.

--[no]color, --[no]colour

--color highlights the matching text. --nocolor suppressesthe color. This is on by default unless the output is redirected.

On Windows, this option is off by default unless theWin32::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-lineno=color

Sets the color to be used for line numbers.

--[no]column

Show the column number of the first match. This is helpful foreditors that can place your cursor at a given position.

--create-ackrc

Dumps the default ack options to standard output. This is useful forwhen you want to customize the defaults.

--dump

Writes the list of options loaded and where they came from to standardoutput. Handy for debugging.

--[no]env

--noenv disables all environment processing. No .ackrc isread and all environment variables are ignored. By default, ackconsiders .ackrc and settings in the environment.

--flush

--flush flushes output immediately. This is off by defaultunless ack is running interactively (when output goes to a pipe orfile).

-f

Only print the files that would be searched, without actually doingany searching. PATTERN must not be specified, or it will be takenas a path to search.

--files-from=FILE

The list of files to be searched is specified in FILE. The list offiles are separated by newlines. If FILE is "-", the list is loadedfrom standard input.

--[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 filesor directories were specified on the command line.

This is off by default.

-g PATTERN

Print searchable files where the relative path + filename matchesPATTERN.

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, .jpgfiles, "-g" will not list .jpg files either. ack is not intendedto be a general-purpose file finder.

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

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

--[no]group

--group groups matches by file name. This is the defaultwhen used interactively.

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

-H, --with-filename

Print the filename for each match. This is the default unless searchinga single explicitly specified file.

-h, --no-filename

Suppress the prefixing of filenames on output when multiple files aresearched.

--[no]heading

Print a filename heading above each file's results. This is the defaultwhen used interactively.

--help, -?

Print a short help statement.

--help-types, --help=types

Print all known types.

-i, --ignore-case

Ignore case distinctions in PATTERN

--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 wantto customize ack.

--[no]ignore-dir=DIRNAME, --[no]ignore-directory=DIRNAME

Ignore directory (as CVS, .svn, etc are ignored). May be usedmultiple times to ignore multiple directories. For example, masonusers may wish to include --ignore-dir=data. The --noignore-diroption allows users to search directories which would normally beignored (perhaps to research the contents of .svn/props directories).

The DIRNAME must always be a simple directory name. Nesteddirectories like foo/bar are NOT supported. You would need tospecify --ignore-dir=foo and then no files from any foo directoryare taken into account by ack unless given explicitly on the commandline.

--ignore-file=FILTERTYPE:FILTERARGS

Ignore files matching FILTERTYPE:FILTERARGS. The filters are specifiedidentically 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. This isequivalent to the default behavior found in ack 1.

--lines=NUM

Only print line NUM of each file. Multiple lines can be given withmultiple --lines options or as a comma separated list (--lines=3,5,7).--lines=4-7 also works, as well as any combination(--lines=3,15-20,43) The lines are always output in ascending order, nomatter the order given on the command line. No pattern is matched.

-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 theregex as your first argument, e.g. when executing multiple searches over thesame 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

Stop reading a file after NUM matches.

--man

Print this manual page.

-n, --no-recurse

No descending into subdirectories.

-o

Show only the part of each line matching PATTERN (turns off texthighlighting)

--output=expr

Output the evaluation of expr for each line (turns off texthighlighting)If PATTERN matches more than once then a line is output for each non-overlapping match.For more information please see the section "Examples of --output".

--pager=program, --nopager

--pager directs ack's output through program. This can also be specifiedvia the "ACK_PAGER" and "ACK_PAGER_COLOR" environment variables.

Using --pager does not suppress grouping and coloring like pipingoutput 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. Highlightingwill still work, though, so it can be used to highlight matches whilestill 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 (filename output). The filenamesare output separated with a null byte instead of the usual newline. This ishelpful when dealing with filenames that contain whitespace, e.g.

    # remove all files of type html    ack -f --html --print0 | xargs -0 rm -f

-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 forcompatibility with grep. You can also use it for turning --no-recurse off.

-s

Suppress error messages about nonexistent or unreadable files. This is takenfrom fgrep.

--[no]smart-case, --no-smart-case

Ignore case in the search strings if PATTERN contains no uppercasecharacters. This is similar to "smartcase" in vim. This option isoff by default, and ignored if "-i" is specified.

-i always overrides this option.

--sort-files

Sorts the found files lexicographically. Use this if you want your filelistings to be deterministic between runs of ack.

--show-types

Outputs the filetypes that ack associates with each file.

Works with -f and -g options.

--type=[no]TYPE

Specify the types of files to include or exclude from a search.TYPE is a filetype, like perl or xml. --type=perl canalso be specified as --perl, and --type=noperl can be doneas --noperl.

If a file is of both type ``foo'' and ``bar'', specifying --foo and--nobar will exclude the file, because an exclusion takes precedenceover an inclusion.

Type specifications can be repeated and are ORed together.

See ack --help=types for a list of valid types.

--type-add TYPE:FILTER:FILTERARGS

Files with the given FILTERARGS applied to the given FILTERare recognized as being of (the existing) type TYPE.See also ``Defining your own types''.

--type-set TYPE:FILTER:FILTERARGS

Files with the given FILTERARGS applied to the given FILTER are recognized asbeing of type TYPE. This replaces an existing definition for type TYPE. Seealso ``Defining your own types''.

--type-del TYPE

The filters associated with TYPE are removed from Ack, and are no longer consideredfor searches.

-v, --invert-match

Invert match: select non-matching lines

--version

Display version and copyright information.

-w, --word-regexp

Turn on ``words mode''. This sometimes matches a whole word, but thesemantics is quite subtle. If the passed regexp begins with a wordcharacter, then a word boundary is required before the match. If thepassed regexp ends with a word character, or with a word characterfollowed by newline, then a word boundary is required after the match.

Thus, for example, -w with the regular expression "ox" will notmatch the strings "box" or "oxen". However, if the regularexpression is "(ox|ass)" then it will match those strings. Becausethe regular expression's first character is "(", the -w flag hasno effect at the start, and because the last character is ")", it hasno effect at the end.

Force PATTERN to match only whole words. The PATTERN is wrapped with"\b" metacharacters.

-x

An abbreviation for --files-from=-; the list of files to search are readfrom standard input, with one line per file.

-1

Stops after reporting first match of any kind. This is differentfrom --max-count=1 or -m1, where only one match per file isshown. Also, -1 works with -f and -g, where -m doesnot.

--thpppt

Display the all-important Bill The Cat logo. Note that the exactspelling of --thpppppt is not important. It's checked againsta 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 prependedto the command line before processing. Multiple options may liveon multiple lines. Lines beginning with a # are ignored. A .ackrcmight 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 linein the .ackrc file is interpreted as one element of @ARGV.

ack looks in several locations for .ackrc files; the searchingprocess is detailed in ``ACKRC LOCATION SEMANTICS''. Thesefiles 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 predefinedtypes. This is done with command line options that are best put intoan .ackrc file - then you do not have to define your types over andover again. In the following examples the options will always be shownon 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 createa filetype of ``cobol'', you can specify --type=cobol or simply--cobol. File types must be at least two characters long. Thisis why the C language is --cc and the R language is --rr.

ack --perl foo searches for foo in all perl files. ack --help=typestells you, that perl files are files endingin .pl, .pm, .pod or .t. So what if you would like to include .xsfiles as well when searching for --perl files? ack --type-add perl:ext:xs --perl foodoes this for you. --type-add appendsadditional extensions to an existing type.

If you want to define a new type, or completely redefine an existingtype, then use --type-set. ack --type-set eiffel:ext:e,eiffel definesthe type eiffel to include files withthe extensions .e or .eiffel. So to search for all eiffel filescontaining the word Bertrand use ack --type-set eiffel:ext:e,eiffel --eiffel Bertrand.As usual, you can also write --type=eiffelinstead of --eiffel. Negation also works, so --noeiffel excludesall eiffel files from a search. Redefining also works: ack --type-set cc:ext:c,hand .xs files no longer belong to the type cc.

When defining your own types in the .ackrc file you have to usethe 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 (like ack 1.x allowed), ack 2offers additional filter types. The generic syntax is--type-set TYPE:FILTER:FILTERARGS; FILTERARGS depends on the valueof FILTER.

is:FILENAME

is filters match the target filename exactly. It takes exactly oneargument, 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 listof 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 aregular expression. Like match, the regular expression is madecase insensitive.

Example:

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

More filter types may be made available in the future.

ENVIRONMENT VARIABLES

For commonly-used ack options, environment variables can make lifemuch easier. These variables are ignored if --noenv is specifiedon the command line.

ACKRC

Specifies the location of the user's .ackrc file. If this file doesn'texist, ack looks in the default location.

ACK_OPTIONS

This variable specifies default options to be placed in front ofany explicit options on the command line.

ACK_COLOR_FILENAME

Specifies the color of the filename when it's printed in --groupmode. By default, it's ``bold green''.

The recognized attributes are clear, reset, dark, bold, underline,underscore, blink, reverse, concealed black, red, green, yellow,blue, magenta, on_black, on_red, on_green, on_yellow, on_blue,on_magenta, on_cyan, and on_white. Case is not significant.Underline and underscore are equivalent, as are clear and reset.The color alone sets the foreground color, and on_color sets thebackground color.

This option can also be set with --color-filename.

ACK_COLOR_MATCH

Specifies the color of the matching text when printed in --colormode. By default, it's ``black on_yellow''.

This option can also be set with --color-match.

See ACK_COLOR_FILENAME for the color specifications.

ACK_COLOR_LINENO

Specifies the color of the line number when printed in --colormode. By default, it's ``bold yellow''.

This option can also be set with --color-lineno.

See ACK_COLOR_FILENAME for the color specifications.

ACK_PAGER

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

Using "ACK_PAGER" does not suppress grouping and coloring likepiping output on the command-line does, except that on Windowsack 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 coloringlike piping output on the command-line does.

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

AVAILABLE COLORS

ack uses the colors available in Perl's Term::ANSIColor module, whichprovides the following listed values. Note that case does not matter when usingthese values.

Foreground colors

    black  red  green  yellow  blue  magenta  cyan  white    bright_black  bright_red      bright_green  bright_yellow    bright_blue   bright_magenta  bright_cyan   bright_white

Background colors

    on_black  on_red      on_green  on_yellow    on_blue   on_magenta  on_cyan   on_white    on_bright_black  on_bright_red      on_bright_green  on_bright_yellow    on_bright_blue   on_bright_magenta  on_bright_cyan   on_bright_white

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 ackknows about, but you may use other default flags. Now you can searchwith 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 returnsshell return or exit code of 0 only if something is found and 1 ifno 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 onefile 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.

Use --noenv

Your environment variables and .ackrc may be doing things you'renot expecting, or forgotten you specified. Use --noenv to ignoreyour environment and .ackrc.

Use -f to see what files have been selected

Ack's -f was originally added as a debugging tool. If ack isnot finding matches you think it should find, run ack -f to seewhat 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 loadedfrom them.So for example you can find a list of directories that do not get searched or where filetypes are defined.

TIPS

Use the .ackrc file.

The .ackrc is the place to put all your options you use most ofthe time but don't want to remember. Put all your --type-add and--type-set definitions in it. If you like --smart-case, set itthere, too. I also set --sort-files there.

Use -f for working with big codesets

Ack does more than search files. "ack -f --perl" will create alist of all the Perl files in a tree, ideal for sending into xargs.For example:

    # Change all "this" to "that" in all Perl files in a tree.    ack -f --perl | xargs perl -p -i -e's/this/that/g'

or if you prefer:

    perl -p -i -e's/this/that/g' $(ack -f --perl)

Use -Q when in doubt about metacharacters

If you're searching for something with a regular expressionmetacharacter, most often a period in a filename or IP address, addthe -Q to avoid false positives without all the backslashing. Seethe following example for more...

Use ack to watch log files

Here's one I used the other day to find trouble spots for a websitevisitor. The user had a problem loading troublesome.gif, so Itook the access log and scanned it with ack twice.

    ack -Q aa.bb.cc.dd /path/to/access.log | ack -Q -B5 troublesome.gif

The first ack finds only the lines in the Apache log for the givenIP. The second finds the match on my troublesome GIF, and showsthe previous five lines from the log in each case.

Examples of --output

Following variables are useful in the expansion string:

$&: The whole string matched by PATTERN.
$1, $2, ...: The contents of the 1st, 2nd ... bracketed group in PATTERN.
"$`": The string before the match.
"$'": The string after the match.

For more details and other variables see<http://perldoc.perl.org/perlvar.html#Variables-related-to-regular-expressions|perlvar>.

This example shows how to add text around a particular pattern(in this case adding _ around word with ``e'')

    ack2.pl "\w*e\w*" quick.txt --output="$`_$&_$'"    _The_ quick brown fox jumps over the lazy dog    The quick brown fox jumps _over_ the lazy dog    The quick brown fox jumps over _the_ lazy dog

This shows how to pick out particular parts of a match using ( ) within regular expression.

  ack '=head(\d+)\s+(.*)' --output=' $1 : $2'  input file contains "=head1 NAME"  output  "1 : NAME"

COMMUNITY

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

FAQ

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 isintelligent in what files it will search and which ones it won't, butsometimes that can be surprising.

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

NOTE: If you're using an old ack before 2.0, it's probably because it's ofa type that ack doesn't recognize. In ack 1.x, the searching behavior isdriven by filetype. If ack 1.x doesn't know what kind of file it is,ack ignores the file. You can use the "--show-types" switch to showwhich type ack thinks each file is.

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

No, ack will always be read-only. Perl has a perfectly good wayto do search & replace in files, using the "-i", "-p" and "-n"switches.

You can certainly use ack to select your files to update. Forexample, to change all ``foo'' to ``bar'' in all PHP files, you can dothis 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''. If you thinkthat ack should recognize a type by default, please see``ENHANCEMENTS''.

There's already a program/package called ack.

Yes, I know.

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 packageout there called ``ack'' that has nothing to do with this ack.

I suggest you make a symlink named ack that points to ack-grepbecause one of the crucial benefits of ack is having a name that'sso 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 couldpronounce as a single syllable.

Can I do multi-line regexes?

No, ack does not support regexes that match multiple lines. Doingso 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 youwould like to search for these, you may prefix your search term with "--" oruse the "--match" option. (However, don't forget that "+" is a regularexpression metacharacter!)

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

The Perl language limits the repetition quantifier to 32K. Youcan 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, pleasebring it up on the ack-users mailing list.

ACKRC LOCATION SEMANTICS

Ack can load its configuration from many sources. The following listspecifies the sources Ack looks for configuration files; each onethat is found is loaded in the order specified here, andeach one overrides options set in any of the sources precedingit. (For example, if I set --sort-files in my user ackrc, and--nosort-files on the command line, the command line takesprecedence)

•

Defaults are loaded from App::Ack::ConfigDefaults. This can be omittedusing "--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 specifiedwith 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 isthe first ackrc file with the name ".ackrc" or "_ackrc", first searchingin the current directory, then the parent directory, then the grandparentdirectory, etc. This can be omitted using "--noenv".

•

--ackrc

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

•

ACK_OPTIONS

Options are then loaded from the environment variable "ACK_OPTIONS". This canbe omitted using "--noenv".

•

Command line

Options are then loaded from the command line.

DIFFERENCES BETWEEN ACK 1.X AND ACK 2.X

A lot of changes were made for ack 2; here is a list of them.

GENERAL CHANGES

•: When no selectors are specified, ack 1.x only searches through files thatit can map to a file type. ack 2.x, by contrast, will search throughevery regular, non-binary file that is not explicitly ignored via--ignore-file or --ignore-dir. This is similar to the behavior of the-a/--all option in ack 1.x.
•: A more flexible filter system has been added, so that more powerful file typesmay be created by the user. For details, please consult``Defining your own types''.
•: ack now loads multiple ackrc files; see ``ACKRC LOCATION SEMANTICS'' fordetails.
•: ack's default filter definitions aren't special; you may tell ack tocompletely disregard them if you don't like them.

REMOVED OPTIONS

•: Because of the change in default search behavior, the -a/--all and-u/--unrestricted options have been removed. In addition, the-k/--known-types option was added to cause ack to behave withthe default search behavior of ack 1.x.
•: The -G option has been removed. Two regular expressions on thecommand line was considered too confusing; to simulate -G's functionality,you may use the new -x option to pipe filenames from one invocation ofack into another.
•: The --binary option has been removed.
•: The --skipped option has been removed.
•: The --text option has been removed.
•: The --invert-file-match option has been removed. Instead, you mayuse -v with -g.

CHANGED OPTIONS

•: The options that modify the regular expression's behavior (-i, -w,-Q, and -v) may now be used with -g.

ADDED OPTIONS

•: --files-from was added so that a user may submit a list of filenames asa list of files to search.
•: -x was added to tell ack to accept a list of filenames via standard input;this list is the list of filenames that will be used for the search.
•: -s was added to tell ack to suppress error messages about non-existent orunreadable files.
•: --ignore-directory and --noignore-directory were added as aliases for--ignore-dir and --noignore-dir respectively.
•: --ignore-file was added so that users may specify patterns of files toignore (ex. /.*~$/).
•: --dump was added to allow users to easily find out which options areset where.
•: --create-ackrc was added so that users may create custom ackrc files basedon the default settings loaded by ack, and so that users may easily view thosedefaults.
•: --type-del was added to selectively remove file type definitions.
•: --ignore-ack-defaults was added so that users may ignore ack's defaultoptions in favor of their own.
•: --bar was added so ack users may consult Admiral Ackbar.

AUTHOR

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

BUGS

Please report any bugs or feature requests to the issues list atGithub: <https://github.com/beyondgrep/ack2/issues>

ENHANCEMENTS

All enhancement requests MUST first be posted to the ack-usersmailing list at <http://groups.google.com/group/ack-users>. Iwill not consider a request without it first getting seen by otherack users. This includes requests for new filetypes.

There is a list of enhancements I want to make to ack in the ackissues list at Github: <https://github.com/beyondgrep/ack2/issues>

Patches are always welcome, but patches with tests get the mostattention.

SUPPORT

Support for and information about ack can be found at:

•: The ack homepage
<https://beyondgrep.com/>
•: The ack-users mailing list
<http://groups.google.com/group/ack-users>
•: The ack issues list at Github
<https://github.com/beyondgrep/ack2/issues>
•: AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/ack>
•: CPAN Ratings
<http://cpanratings.perl.org/d/ack>
•: Search CPAN
<http://search.cpan.org/dist/ack>
•: MetaCPAN
<http://metacpan.org/release/ack>
•: Git source repository
<https://github.com/beyondgrep/ack2>

ACKNOWLEDGEMENTS

How appropriate to have acknowledgements!

Thanks to everyone who has contributed to ack in any way, includingTim Gim Yee,Michele Campeotto,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 andRob Hoelz.