Sed/Awk manipulation of a text

Question

I need to change the last column of a file:

dir_/agra_2008_04_07_a  6   scd679  Voice of male
dir_/agra_2008_04_07_a  7   scd680  voice off
dir_/agra_2007_10_01_a  2   scd502  voice over
dir_/agra_2007_10_08_a  2   scd502  voice over

to this other:

dir_/agra_2008_04_07_a  6   scd679  Voice_of_male
dir_/agra_2008_04_07_a  7   scd680  voice_off
dir_/agra_2007_10_01_a  2   scd502  voice_over
dir_/agra_2007_10_08_a  2   scd502  voice_over

Adding underscores to the last column! Anyone? Thank you!

Answer 1

A simple sed solution:

sed 's/ /_/8g' file

It replaces spaces with underscores, but ignoring the first 7 occrences, hence starting with the 8th to the end ( g ). It works if your output has always the same number of spaces until the last column.

Answer 2

As long as you have double space as field separator you can use this awk

awk -F"  " '{gsub(/ /,"_",$NF)}1' OFS="  " file
dir_/agra_2008_04_07_a  6   scd679  Voice_of_male
dir_/agra_2008_04_07_a  7   scd680  voice_off
dir_/agra_2007_10_01_a  2   scd502  voice_over
dir_/agra_2007_10_08_a  2   scd502  voice_over

It replace space on last filed with _