|ACK(1)||User Contributed Perl Documentation||ACK(1)|
ack [options] PATTERN [FILE...] ack -f [options] [DIRECTORY...]
ack searches the named input files or directories 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 <http://perldoc.perl.org/perlreref.html|perlreref>. If you don't know how to use regular expression but are interested in learning, you may consult <http://perldoc.perl.org/perlretut.html|perlretut>. 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.
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.
For a complete list of directories that do not get searched, run "ack --dump".
E.g., searching through huge files looking for regexes that can be expressed 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.
- 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.
- 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.
- Sets the color to be used for filenames.
- Sets the color to be used for matches.
- Sets the color to be used for line numbers.
- Show the column number of the first match. This is helpful for editors that can place your cursor at a given position.
- Dumps the default ack options to standard output. This is useful for when you want to customize the defaults.
- Writes the list of options loaded and where they came from to standard output. Handy for debugging.
- --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 flushes output immediately. This is off by default unless ack is running interactively (when output goes to a pipe or file).
- 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.
- 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.
- Forces ack to act as if it were receiving input via a pipe.
- 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
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.
- --group groups matches by file name. This is the default when used
--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.
- Print a filename heading above each file's results. This is the default when used interactively.
- --help, -?
- Print a short help statement.
- --help-types, --help=types
- Print all known types.
- -i, --ignore-case
- Ignore case distinctions in PATTERN
- 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 files matching FILTERTYPE:FILTERARGS. 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. This is equivalent to the default behavior found in ack 1.
- Only print line NUM of each file. Multiple lines can be given with multiple --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, no matter 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 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
- Stop reading a file after NUM matches.
- Print this manual page.
- -n, --no-recurse
- No descending into subdirectories.
- Show only the part of each line matching PATTERN (turns off text highlighting)
- 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. For more information please see the section "Examples of --output".
- --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.
- 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 18.104.22.168
- Only works in conjunction with -f, -g, -l or -c (filename output). The
filenames are output separated with a null byte instead of the usual
newline. This is helpful when dealing with filenames that contain
# 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 for compatibility with grep. You can also use it for turning --no-recurse off.
- Suppress error messages about nonexistent or unreadable files. This is taken from fgrep.
- --[no]smart-case, --no-smart-case
- Ignore case in the search strings if PATTERN contains no uppercase
characters. This is similar to
"smartcase" in vim. This option is off
by default, and ignored if "-i" is
-i always overrides this option.
- Sorts the found files lexicographically. Use this if you want your file listings to be deterministic between runs of ack.
- Outputs the filetypes that ack associates with each file.
Works with -f and -g options.
- Specify the types of files to include or exclude from a search. TYPE is a
filetype, like perl or xml. --type=perl can also be
specified as --perl, and --type=noperl can be done as
If a file is of both type "foo" and "bar", specifying --foo and --nobar will exclude the file, because an exclusion takes precedence over 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 FILTER are 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 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.
- -v, --invert-match
- Invert match: select non-matching lines
- Display version and copyright information.
- -w, --word-regexp
- Turn on "words mode". This sometimes matches a whole word, but
the semantics is quite subtle. If the passed regexp begins with a word
character, then a word boundary is required before the match. If the
passed regexp ends with a word character, or with a word character
followed by newline, then a word boundary is required after the match.
Thus, for example, -w with the regular expression "ox" will not match the strings "box" or "oxen". However, if the regular expression is "(ox|ass)" then it will match those strings. Because the regular expression's first character is "(", the -w flag has no effect at the start, and because the last character is ")", it has no effect at the end.
Force PATTERN to match only whole words. The PATTERN is wrapped with "\b" metacharacters.
- An abbreviation for --files-from=-; the list of files to search are read from standard input, with one line per file.
- Stops after reporting first match of any kind. This is different from --max-count=1 or -m1, where only one match per file is shown. Also, -1 works with -f and -g, where -m does not.
- 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.
- Check with the admiral for traps.
- Chocolate, Chocolate, Chocolate!
# 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.
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:
or writing on separate lines
The following does NOT work in the .ackrc file:
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 2 offers additional filter types. The generic syntax is --type-set TYPE:FILTER:FILTERARGS; FILTERARGS depends on the value of FILTER.
- is filters match the target filename exactly. It takes exactly one
argument, which is the name of the file to match.
- ext filters match the extension of the target file against a list
of extensions. No leading dot is needed for the extensions.
- match filters match the target filename against a regular
expression. The regular expression is made case insensitive for the
- firstlinematch matches the first line of the target file against a
regular expression. Like match, the regular expression is made case
More filter types may be made available in the future.
- Specifies the location of the user's .ackrc file. If this file doesn't exist, ack looks in the default location.
- This variable specifies default options to be placed in front of any explicit options on the command line.
- Specifies the color of the filename when it's printed in --group
mode. 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 the background color.
This option can also be set with --color-filename.
- Specifies the color of the matching text when printed in --color
mode. By default, it's "black on_yellow".
This option can also be set with --color-match.
See ACK_COLOR_FILENAME for the color specifications.
- Specifies the color of the line number when printed in --color
mode. By default, it's "bold yellow".
This option can also be set with --color-lineno.
See ACK_COLOR_FILENAME for the color specifications.
- Specifies a pager program, such as
"most", to which ack will send its
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.
- 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".
black red green yellow blue magenta cyan white bright_black bright_red bright_green bright_yellow bright_blue bright_magenta bright_cyan bright_white
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
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
(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.
# 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)
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 given IP. The second finds the match on my troublesome GIF, and shows the previous five lines from the log in each case.
- 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"
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.
NOTE: If you're using an old ack before 2.0, it's probably because it's of a type that ack doesn't recognize. In ack 1.x, the searching behavior is driven 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 show which type ack thinks each file is.
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' $(ack -f --php)
I suggest you make a symlink named ack that points to ack-grep because one of the crucial benefits of ack is having a name that's so short and simple to type.
To do that, run this with sudo or as root:
ln -s /usr/bin/ack-grep /usr/bin/ack
Alternatively, you could use a shell alias:
# bash/zsh alias ack=ack-grep # csh alias ack ack-grep
If you want to see lines near your match, use the "--A", "--B" and "--C" switches for displaying context.
- Defaults are loaded from App::Ack::ConfigDefaults. This can be omitted using "--ignore-ack-defaults".
- Global ackrc
Options are then loaded from the global ackrc. This is located at "/etc/ackrc" on Unix-like systems.
Under Windows XP and earlier, the global ackrc is at "C:\Documents and Settings\All Users\Application Data\ackrc"
Under Windows Vista/7, the global ackrc is at "C:\ProgramData\ackrc"
The "--noenv" option prevents all ackrc files from being loaded.
- User ackrc
Options are then loaded from the user's ackrc. This is located at "$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".
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.
Options are then loaded from the environment variable "ACK_OPTIONS". This can be omitted using "--noenv".
- Command line
Options are then loaded from the command line.
- When no selectors are specified, ack 1.x only searches through files that it can map to a file type. ack 2.x, by contrast, will search through every 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 types may be created by the user. For details, please consult "Defining your own types".
- ack now loads multiple ackrc files; see "ACKRC LOCATION SEMANTICS" for details.
- ack's default filter definitions aren't special; you may tell ack to completely disregard them if you don't like them.
- 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 with the default search behavior of ack 1.x.
- The -G option has been removed. Two regular expressions on the command line was considered too confusing; to simulate -G's functionality, you may use the new -x option to pipe filenames from one invocation of ack 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 may use -v with -g.
- The options that modify the regular expression's behavior (-i, -w, -Q, and -v) may now be used with -g.
- --files-from was added so that a user may submit a list of filenames as a 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 or unreadable 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 to ignore (ex. /.*~$/).
- --dump was added to allow users to easily find out which options are set where.
- --create-ackrc was added so that users may create custom ackrc files based on the default settings loaded by ack, and so that users may easily view those defaults.
- --type-del was added to selectively remove file type definitions.
- --ignore-ack-defaults was added so that users may ignore ack's default options in favor of their own.
- --bar was added so ack users may consult Admiral Ackbar.
There is a list of enhancements I want to make to ack in the ack issues list at Github: <https://github.com/beyondgrep/ack2/issues>
Patches are always welcome, but patches with tests get the most attention.
- The ack homepage
- The ack-users mailing list
- The ack issues list at Github
- AnnoCPAN: Annotated CPAN documentation
- CPAN Ratings
- Search CPAN
- Git source repository
Thanks to everyone who has contributed to ack in any way, including Tim 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 and Rob Hoelz.
This program is free software; you can redistribute it and/or modify it under the terms of the Artistic License v2.0.
See http://www.perlfoundation.org/artistic_license_2_0 or the LICENSE.md file that comes with the ack distribution.