http://www.unix.com – please solve my problem i have a sample input file as A A A A B B B B B C C C C C i want the output such that if the count of A or B or C is greater than 3 A A A B B B C C C if the count of A is less than 3 i.e if the input file is like A A B B B B C C C then A should append B and the output file should be A A B B B B C C C the above output should repeat for both B and C too if the count of B and C is also less than 3 thanks in advance sai (HowTos)