Question

I’ve a file with 2 lines having key, value pair on each line. “//” is used as comment style.

1. key = "string_key_value" //string key

How can I extract string_key_value without quotes?

2. key =100 //integer value

How can I extract 100 from here as an integer?

I’ve to re-use these values in another unix command.

Answer 1

Try this:

perl -wlne'print $1 if /key\s*=\s*\"?([^\"; ]+)[\" ;]/' source.cpp

It pulls out everything after key = and before a closing quote/space/semicolon. if you’ve got strings with escaped quotes, this will fail, so this should only be used if you need a quick and dirty solution. If you are parsing production data, log files etc, you should use a module in the Parse:: family on CPAN, rather than using regular expressions.

I’ve to re-use these values in another unix command.

Perhaps you should be defining these values in a central location (like a constants file, or a config file), rather than attempting to parse source code.. it would be far less error-prone (not to mention hacky).