From: "Stephane Tsacas" <stephane.tsacas(a)gmail.com> I guess you have hex digit as input, not prefixed by 0x (if they are, remove the string "0x" from the x= statement. Maybe that code might help : awk --non-decimal-data 'BEGIN {RS=" ";} {x="0x"$0; s=""; while (x > 0) { s=and(x,1)""s; x=rshift(x,1); } print s}' 0 1 2 3 4 5 6 7 8 9 a b c d e f as input will print : 0 1 10 11 100 101 110 111 1000 1001 1010 1011 1100 1101 1110 1111 you can put your own code after the x= statement I guess. Stephane