>perl -nle "print ' ==> ', eval"
print 2
2
 ==> 1
'12a34' =~ /(\d)/
 ==> 1
'12a34' =~ /(\d+)/
 ==> 12
'12a34' =~ /(\d+$)/
 ==> 34
'12a34' =~ /(\d+ $)/x
 ==> 34