Regular expression question

Question

Hi,

I am trying to use the cscope-indexer script. But I want to know how to change the following to include *.mm and *.java files?

egrep -i '\.([chly](xx|pp)*|cc|hh)$' | \
sed -e '/\/CVS\//d' -e '/\/RCS\//d' -e 's/^\.\///' | \
sort > $LIST_FILE

I tried

egrep -i '\.([chly](xx|pp)*|cc|hh|mm|java)$'

it does not work.

Answer 1

Try:

egrep -i '\.([chly](xx|pp)*|cc|hh|mm|java)$' | \
sed -e '/\/CVS\//d' -e '/\/RCS\//d' -e 's/^\.\///' | \
sort > $LIST_FILE

Answer 2

When you saw [chly] in the original regex, that meant "either a 'c', an 'h', an 'l', or a 'y'. When changed it to "chly*", it now meant "chl" followed by any number of y's. Also, when you removed the '\' from in front of the first period, you changed it's meaning from "match a period" to "match one of any character".

For more information on regexes, check out the Perl Regular Expression Guide, since Perl pretty much invented regular expressions.