BEGIN { W = 14 } { for (i=1; i<=length($1); i++) { window = substr($1,i,W) # compare each char of window to all char of window S = 0 # to count match for (j=1; j<=W; j++) { for (k=1; k<=W; k++) { S+= (substr(window,j,1) == substr(window,k,1)) ? 1 : 0 } } if (S == W) { # if each char match only with itsef print i + W - 1 next # finish } } }