Question

Actually my question is quite simple:
I have a string like: 101222_1_1_ab;
I hope to change it into: 101222_1_ab_1

What bash commands should I use? and what to do in python?
THanks

Answer 1

The easiest mechanism I can think of is to use awk(1):

$ echo 101222_1_1_ab | awk -F_ '{print $1 "_" $2 "_" $4 "_" $3;}'
101222_1_ab_1

The -F_ asks awk(1) to split fields apart on underscores.

Update Glenn Jackman recommends the following, far more legible, version:

awk -F_ -v OFS=_ '{print $1, $2, $4, $3}'