Replacing specific spaces with colons in a text file

Question

I have a report that outputs to a text file in linux and I need it modified a bit.

The file starts out like this if you cat it:

  6 E8 B7 48 36 8C AE
  8 00 0C 85 F2 F9 07
  8 44 03 A7 C0 0D 26
  8 C8 4C 75 5C B1 55
 10 00 05 00 E7 5B 9F
 10 00 17 C5 69 49 A1
 10 00 1D A2 E7 BC F1
 12 00 16 9C 6C 53 C0
 14 00 0C 85 F2 F9 08
 26 00 05 00 E7 5B B7

Some random text will be down here also...

I'm wanting it to look like this:

  6 E8:B7:48:36:8C:AE
  8 00:0C:85:F2:F9:07
  8 44:03:A7:C0:0D:26
  8 C8:4C:75:5C:B1:55
 10 00:05:00:E7:5B:9F
 10 00:17:C5:69:49:A1
 10 00:1D:A2:E7:BC:F1
 12 00:16:9C:6C:53:C0
 14 00:0C:85:F2:F9:08
 26 00:05:00:E7:5B:B7

Some random text will be down here also...

I was hoping to use sed to accomplish this.

Answer 1

One way using sed:

sed 's/  */:/3g'  file

Answer 2

I think this would be easier with awk:

awk '{ printf("%2.2s %s:%s:%s:%s:%s:%s\n", $1, $2, $3, $4, $5, $6, $7); }' file

Answer 3

Following the answer of @Guru, you can try this one with sed:

sed -r 's/(\w) +/\1:/2g' file

You have to catch one letter before as sed does not support lookbehind.

Answer 4

Using Perl, this will work with any number of alignment spaces:

perl -lane '($p,$m)=/^(\s*\d+\s*)(.*)$/; $m =~ s/ /:/g; print $p,$m' input

Answer 5

sed "
: doublept
   s/^\( *[[:digit:]]\{1,\}\)\( \{1,\}\)\(.*\) \([[:alnum:]]\{1,\}\)/\1\2\3:\4/
   t doublept
"

work also for bigger "mac address" if any (i think mainly same kind of problem for IP adress and IPv6)

Answer 6

If you always know the line range for the numbers, you can use:-

sed 1,10s'/ /:/'g

The single quotes are important.