Hi all, I have a tab separated file, and one of the fields is sub-delimited by colon. The problem is there can be zero to 4 colons within this field. When I try to change colons to tabs the result is a file with a differing number of fields.

I want to go from:

a:b:c:d:e
a:b:c
a:b:c:d:e
a
a:b:c:d:e

a    b     c     d     e
a    b     c     .     .
a    b     c     d     e
a    .     .     .     .
a    b     c     d     e

awk -F ":" 'NF<5{for(i=(NF+1);i<=5;i++){$i="."}}{$1=$1}1' OFS="\t" file

That seems to work perfectly!! Thanks so much.

this works for n number of columns

$ n=$(awk -F: 'NF>a{a=NF}END{print a}' input.txt);
$ awk -F: -v n="$n" '{for(i=1i<=n;i++)if($i=="")$i="."}NF==n{gsub(":"," ")}1' input.txt
a b c d e f g h i . .
a b c . . . . . . . .
a b c d e . . . . . .
a . . . . . . . . . .
a b c d e . . . . . .
a b c d e f g h i j k

$ cat a.txt
a:b:c:d:e:f:g:h:i
a:b:c
a:b:c:d:e
a
a:b:c:d:e
a:b:c:d:e:f:g:h:i:j:k

works great, thanks so much.