Grr was written by Daniel Walker.
Version 2.1.7 was released on October 21, 2021.

Grr takes a regex and searches a directory tree for files containing strings which match that regex.  All
lines which contain a match are printed to the screen in the following format:

(5) some/directory/file.txt (line 97) : ... k19jIMATCHTHEREGEXkjljlk ...

The "(5)" is a result number.  The first result printed will be numbered 0, then 1, and so on.  The purpose
of this numbering system will be explained below under the "-l" option description.

=== USAGE ===

grr [options]

Options:
    -r <regex>          Specifies the search regex.  Required unless either -u or -h is used.
    -d <directory>      Specifies the starting directory.  Defaults to the present working directory.
    -p <depth>          Specify the directory search maximum depth.  Defaults to infinite.  A value of 0,
                        for example, means that only the starting directory will be searched.
    -f <regex>          Specifies a regex for matching against the file names which are searched.  Only
                        files which contain a substring which matches the regex will be searched.
    -n                  Only print the names of the files which contain matches.
    -l <result-number>  Instead of printing the results to the screen, the file denoted by the specified
                        result number will be opened in an editor.  The editor used can be set via the EDITOR
                        environment variable or by using the -e option.  If neither are set, vi/m will be
                        used. In the case that vi/m is used, the file will be opened to the line containing
                        the match (or the first line if the -n option was used).
    -e <editor>         Specifies the editor to be used with the -l option.  Has no effect if -l is not used.
    -i                  The directory tree search will ignore all hidden files and folders.
    -y                  Neither read from nor write to the history file.  See "HISTORY FILE" below.
    -c                  Ordinarily, the substring within the file which matched the regex is printed in red.
                        This option disables that coloration.  When stdout is not directed to a terminal,
                        color is disabled automatically.
    -v                  Prints verbose output to stderr.
    -u                  Prints Grr's version.
    -h                  Prints the usage information.

=== HISTORY FILE ===

When doing a normal search (i.e., not using the -l option), a history file named .grr_history is created in
the $HOME directory.  The results of the query in addition to its starting directory, regex, and search
options are written to the file.  If the next invocation of Grr uses the same search parameters but includes
the -l option, Grr merely uses the results stored in the history file in order to fetch the file to be
opened.  The directory tree is therefore not searched.  The next time Grr is run without the -l option, the
contents of the history file will be overwritten.

You can disable the use of the history file via the -y option.  This is useful in the case that the directory
tree's contents have changed since the last search.

=== REGEX GRAMMAR ===

See the README for GrrEngine (https://github.com/nickeldan/grrengine) for a description of the regex grammar.