The "grep" command:

Attempt to match the given POSIX extended regular expression PATTERN over all historic versions of FILENAME. The search begins with the most recent version of the file and moves backwards in time. Multiple FILENAMEs can be specified, in which case all named files are searched in reverse chronological order.

For details of the supported regular expression dialect, see https://fossil-scm.org/fossil/doc/trunk/www/grep.md

Options:

-c|--count

Suppress normal output; instead print a count of the number of matching files

-i|--ignore-case

Ignore case

-l|--files-with-matches

List only hash for each match

--once

Stop searching after the first match

-s|--no-messages

Suppress error messages about nonexistent or unreadable files

-v|--invert-match

Invert the sense of matching. Show only files that have no matches. Implies -l

--verbose

Show each file as it is analyzed