perl -e 'print "ababa\n"' ababa
perl -pe 's/ababa/kapapa/g' < [filename]
perl -pi.bak -e 's/ababa/kapapa/g' [filename]
perl -pi -e 's/ababa/kapapa/g' [filename]
perl -ane 'foreach(@F){print "$_\n";}' < [filename]