For complex expression you need to include the pattern inside the brackets \( and \)
For example:
find /home/karthik -name "*.pl" -o -name "*.pm" -o ! \( -name "*.*" -o -type d \)
Include:
1)include the files ending with .pl and .pm
Exclude:
1)exclude the files ending with any other pattern than the specified "pl" and "pm".
2) to exclude the directories
