Usage: ack [OPTION]... PATTERN [FILE]

Search for PATTERN in each source file in the tree from cwd on down.
If [FILES] is specified, then only those files/directories are checked.
ack may also search STDIN, but only if no FILE are specified, or if
one of FILES is "-".

Default switches may be specified in ACK_OPTIONS environment variable or
an .ackrc file. If you want no dependency on the environment, turn it
off with --noenv.

Example: ack -i select

Searching:
  -i, --ignore-case     Ignore case distinctions in PATTERN
  --[no]smart-case      Ignore case distinctions in PATTERN,
                        only if PATTERN contains no upper case
                        Ignored if -i is specified
  -v, --invert-match    Invert match: select non-matching lines
  -w, --word-regexp     Force PATTERN to match only whole words
  -Q, --literal         Quote all metacharacters; PATTERN is literal

Search output:
  --line=NUM            Only print line(s) NUM of each file
  -l, --files-with-matches
                        Only print filenames containing matches
  -L, --files-without-matches
                        Only print filenames with no matches
  -o                    Show only the part of a line matching PATTERN
                        (turns off text highlighting)
  --passthru            Print all lines, whether matching or not
  --output=expr         Output the evaluation of expr for each line
                        (turns off text highlighting)
  --match PATTERN       Specify PATTERN explicitly.
  -m, --max-count=NUM   Stop searching in each file after NUM matches
  -1                    Stop searching after one match of any kind
  -H, --with-filename   Print the filename for each match
  -h, --no-filename     Suppress the prefixing filename on output
  -c, --count           Show number of lines matching per file
  --column              Show the column number of the first match

  -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.
  -C [NUM], --context[=NUM]
                        Print NUM lines (default 2) of output context.

  --print0              Print null byte as separator between filenames,
                        only works with -f, -g, -l, -L or -c.

File presentation:
  --pager=COMMAND       Pipes all ack output through COMMAND.  For example,
                        --pager="less -R".  Ignored if output is redirected.
  --nopager             Do not send output through a pager.  Cancels any
                        setting in ~/.ackrc, ACK_PAGER or ACK_PAGER_COLOR.
  --[no]heading         Print a filename heading above each file's results.
                        (default: on when used interactively)
  --[no]break           Print a break between results from different files.
                        (default: on when used interactively)
  --group               Same as --heading --break
  --nogroup             Same as --noheading --nobreak
  --[no]color           Highlight the matching text (default: on unless
                        output is redirected, or on Windows)
  --[no]colour          Same as --[no]color
  --color-filename=COLOR
  --color-match=COLOR   Set the color for matches and filenames.
  --flush               Flush output immediately, even when ack is used
                        non-interactively (when output goes to a pipe or
                        file).

File finding:
  -f                    Only print the files found, without searching.
                        The PATTERN must not be specified.
  -g REGEX              Same as -f, but only print files matching REGEX.
  --sort-files          Sort the found files lexically.

File inclusion/exclusion:
  -a, --all-types       All file types searched;
                        Ignores CVS, .svn and other ignored directories
  -u, --unrestricted    All files and directories searched
  --[no]ignore-dir=name Add/Remove directory from the list of ignored dirs
  -r, -R, --recurse     Recurse into subdirectories (ack's default behavior)
  -n, --no-recurse      No descending into subdirectories
  -G REGEX              Only search files that match REGEX

  --perl                Include only Perl files.
  --type=perl           Include only Perl files.
  --noperl              Exclude Perl files.
  --type=noperl         Exclude Perl files.
                        See "ack --help type" for supported filetypes.

  --type-set TYPE=.EXTENSION[,.EXT2[,...]]
                        Files with the given EXTENSION(s) are recognized as
                        being of type TYPE. This replaces an existing
                        definition for type TYPE.
  --type-add TYPE=.EXTENSION[,.EXT2[,...]]
                        Files with the given EXTENSION(s) are recognized as
                        being of (the existing) type TYPE

  --[no]follow          Follow symlinks.  Default is off.

  Directories ignored by default:
    autom4te.cache, blib, _build, .bzr, .cdv, cover_db, CVS, _darcs, ~.dep,
    ~.dot, .git, .hg, ~.nib, .pc, ~.plst, RCS, SCCS, _sgbak and .svn

  Files not checked for type:
    /~$/           - Unix backup files
    /#.+#$/        - Emacs swap files
    /[._].*\.swp$/ - Vi(m) swap files
    /core\.\d+$/   - core dumps

Miscellaneous:
  --noenv               Ignore environment variables and ~/.ackrc
  --help                This help
  --man                 Man page
  --version             Display version & copyright
  --thpppt              Bill the Cat

Exit status is 0 if match, 1 if no match.

This is version 1.90 of ack.
