Rgrep is a clone of the
SLang-based rgrep that ships
with the jed text editor. It was written when I tried
to port the SLang editor to a modern Linux distribution and was
thwarted because the pre-packaged copies of the library were not
complete enough to actually run the program.
Rgrep implements most of the functionality of the reference
program, lacking only {min,max} and \d in the regular
expression language and the long options --version and --help.
It uses Henry Spencer’s BSD-regex library (slightly modified to more
closely resemble the SLang regular expression language) to provide a
slow, but functional, recursive grep.