-d Don't change modification times of altered files,
-q Quiet mode (no output at all),
-s Simulation mode.
-added -w option: doesn't recognize regexp in OLDPATTERN. This option accelerates the whole process. Incompatible with -e and/or -n.
-BUG "Segmentation fault" fixed.
-Binary data support,
-option -v shows loops numbers and datasize to read and write.
-BUG "Segmentation fault" at -r option fixed.
-BUG -r (recursively) fixed.
-You can use "NULL" as [NEWPATTERN] to clear [OLDPATTERN], i.e.:
chgrep oldstring NULL somefile.c
-You can use regular expressions in [OLDPATTERN],
-i Ignore differences in case at [OLDPATTERN],
-n Treat [newline] as a regular character.