For a good start on greedy regexps see Ovid's classic Death to Dot Star!. Essentially the greediness of a regexp relates to the fact that both * and + will match the preceding atom for as long as possible. However you can alter this behaviour by appending either modifier with a question mark e.g

my $str = "123 foo 456 foo 789 foo 10";

# will match everything up to the last 'foo'
print "dot star greedy:     ", $str =~ /(.*)foo/, $/;

# will match everything up to the first 'foo'
print "dot star non-greedy: ", $str =~ /(.*?)foo/, $/;

__output__

dot star greedy:     123 foo 456 foo 789 
dot star non-greedy: 123
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HTH

_________
broquaint

update: made code more illustrative