Ytdyklly

Searching directories

Based on the synopsis shown in the man page I would say yes it can process a directory, but looking at the switches it cannot look for just a file based on a pattern. For that you'll have to enlist find. The command ack does include the option --files-from=FILE so that it can be fed a list of files from find.

synopsis

       ack [options] PATTERN [FILE...]

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

usage

   --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.

There is the --ignore-file= option which may give you what you want but seems a bit of a pain to actually use.

   --ignore-file=FILTERTYPE:FILTERARGS

       Ignore files matching FILTERTYPE:FILTERARGS.  The filters are

       specified identically to file type filters as seen in "Defining

       your own types".

Searching specific types of files

The only other way I can conceive of doing just this via ack is to use its --type switch:

   --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 can also be

       specified as --perl, and --type=noperl can be done as --noperl.



       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.

To see what types are available:

$ ack --help-types | grep -E "perl|cpp"

format. For example, both --type=perl and --perl work.
--[no]cpp .cpp .cc .cxx .m .hpp .hh .h .hxx
--[no]objcpp .mm .h
--[no]perl .pl .pm .pod .t .psgi; first line matches /^#!.*bperl/
--[no]perltest .t

Examples

Find all the Perl files, based on both the filename (*.pm, *.pl, *.t and *.pod) and the shebang line.

$ ack -f --type perl 

examples/iwatch/iwatch/iwatch

examples/nytprof_perl/bad.pl

Find all the C++ files:

$ ack -f --type=cpp

Shared/Scanner.h

Shared/Sorter.h

Shared/DicomHelper.cpp

Shared/DicomDeviationWriter.h

Searching for foo in bar*.c

So then how can you accomplish what you want? Well you'll have to likely use find to do this:

$ find adir -iname "bar*.c" | ack --files-from=- foo

adir/bar1.c

1:foo

2:foo



adir/dir1/bar1.c

1:foo

2:foo

You can also use ack's ability to search for files that match a given pattern in their filenames (using -g <pattern>), and then pass this list to a second invocation of ack using -x or --files-from=-..

Using -x:

$ ack -g 'bbar.*.c$' | ack -x foo

bar1.c

1:foo

2:foo



dir1/bar1.c

1:foo

2:foo

Using -files-from=-:

$ ack -g 'bbar.*.c$' | ack --files-from=- foo

bar1.c

1:foo

2:foo



dir1/bar1.c

1:foo

2:foo

In either case we're matching the filenames that you want using this regex:

bbar.*.c$

This matches files whose name is bar.*c and end after the .c using the end of line anchor, $. We also look to make sure that the names have a boundary character using b. This will fail for files that contain boundary characters such as $bar.c or %bar.c for example.

It's easy if the file type is known, and ack knows a lot of file types. So if, for example, you want to only search in C files, than you can do:

ack --cc 'string'

But if it's not one of the known extensions, you need to define your own type. This should work:

ack --type-set barc:match:/bar.+.c/ --barc 'string'

Note that you need both --type-set and --barc.

(Thanks to Andy, who also helped with this on the mailing list.)

"What's new in ack 2?" http://beyondgrep.com/ack-2.0/

with ack 2.0, you can use the new -x to pipe filenames from one
invocation of ack into another.

ack2 -g -i filepattern | ack2 -x -w searchpattern

Only I can't get it to work:

% ack -g "*bar*.c"

Invalid regex '*bar*.c':

Quantifier follows nothing in regex; marked by <-- HERE in m/* <-- HERE bar*.c/ at ack line 314.

Thus it seems -g needs a regex, while I want a 'glob' style option...

Ack doesn't support glob style file selection. Since I really miss this I created a small shell script ackg:

#!/bin/sh

# 'glob' support for ack

find -name "$2" -type f -exec ack "$1" {} +

Now you can use the command:

ackg foo "bar*.c"

But note: this will unfortunately also search in version control dirs (eg: .git).

Do you want only a certain pattern, or do you just want C source files?

If you want all C files, use

ack --cc foo

If you want all C files and NOT C header files use

ack --cc --no-hh foo

This can be done with the -G option to ag, the silver searcher (an enhanced clone of ack-grep).

$ echo foo > bar_wanted.c

$ echo foo > unwanted.c

$ ag -G "bar.*.c" foo

bar_wanted.c

1:foo

Notes:

• 
  ag uses PCRE regular expression syntax, so the regexp must be bar.*.c instead of bar*.c.


• The -G option needs to precede the search term, as anything after that is interpreted as a filename.

This would seem to be the fastest and safest:

find . -name '*.c' | ack -x 'some string'

-x Read the list of files to search from STDIN.

However, if the file is likely to be in your locate database, this would be even quicker:

locate --basename '*.c' | ack -x 'some thing'

Locate can also accept old-school regular expressions, a little painful, but if you're looking for c files, it might be required.
e.g.

locate --basename --regexp '.(c|cpp|h|hpp|cc)$' |

    ack -x 'some thing'

That just translates to: "search all filename that end in c, cpp, h, hpp or cc."

Using zsh you can do:

ls **/a*.txt | ack --files-from=- something

@chim 's answer is the best, but its written as a comment so I'm reposting as a formal answer...

ack -g 'bbar.*.c$' | ack -x foo

I like the fact that your can regex the path...