in reply to how to search and replace the match with specific number of times in a string

split has an optional LIMIT argument what you can try to utilize something like this: 
perl -le '$s = "abcabdaaa"; $n = 3; print join( "i", split( /a/, $s, $
+n+1 ))'

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See perldoc -f split for details.

In Section Seekers of Perl Wisdom