| Program | Regex Engine |
|---|---|
| awk | DFA |
| egrep | DFA |
| MKS egrep | POSIX NFA |
| grep | Traditional NFA |
| GNU Emacs | Trad. NFA, POSIX NFA available |
| Perl | Traditional NFA |
| Tcl | Traditional NFA |
| Python | Traditional NFA |
| more | Traditional NFA |
* Courtesy of
"Mastering Regular Expressions" by Jeffrey Friedl.