#!/usr/bin/perl -w 

@lines = `perldoc -u -f atan2` ; 
#assigns each line in the perldoc to a $calar variable in th array @lines

#next line starts a loop for every field in the @lines array
#by default this is assigned to the variable $_
foreach (@lines) { 
	s/\w<([^>]+)>/\U$1/g; 
# substitutes a regular expression with <( with the line without this 
	print; # prints the loop varailbe 
	#print $_ ; #would do the same
}