Question

I am getting files like .log and _log in a folder ,i am able to pick .log files with /*.log$/ but unable to find files which are _log .

need a regex pattern which will take both type of files from a specified folder.

Answer 1

Your question is tagged both ‘perl’ and ‘linux’. I’ll assume here that you’re talking about Perl style regular expressions, as it looks like that’s what you are showing in your example snippet.

The *. sequence is a mistake.

Let’s focus on what you want to match. You want to match any filename that ends in a dot followed by the literal characters ‘log’. You also want to match any filename that ends in an underscore, followed by the literal characters ‘log’. You really shouldn’t concern yourself with the “anything at all” that can come before the final dot or underscore. So the regexp would probably be better written as this:

/[._]log$/

Notice we don’t even bother with the dot-star. It isn’t helpful in this situation.

If you want for your pattern to also match files where the literal characters ‘log’ may optionally be followed by an integer sequence (not mentioned in your question, but discussed in one of your followup comments), you could write it like this:

/[._]log\d*$/

Here the ‘star’ is helpful; it allows for zero or more digits sandwiched between the ‘g’ and the end of the string.