Question

I have data like this in tab separated columns:

1   name1   attribute1
1   name1   attribute2
1   name1   attribute3
31  name2   attribute1
31  name2   attribute2
31  name2   attribute3
444 name3   attribute1
444 name3   attribute2
444 name3   attribute3

And I want to have it like this:

001 name1   attribute1
001 name1   attribute2
001 name1   attribute3
031 name2   attribute1
031 name2   attribute2
031 name2   attribute3
444 name3   attribute1
444 name3   attribute2
444 name3   attribute3

Can I do this in unix or perl for instance?

Answer 1

perl -i~ -pe's/^(\d+)/sprintf "%03d", $1/e' file

Actually, the above checks more than it needs to. Here’s a more general solution:

perl -i~ -pe's/^([^\t]*)/sprintf "%03s", $1/e' file