CODEWITHSUNDEEP
bashawk
Sos
Sos

Reputation: 1949

Add string to columns in bash

I have a comma-delimited file to which I want to append a string in specific columns. I am trying to do something like this, but couldn't do it until now.

re1,1,a1e,a2e,AGT
re2,2,a1w,a2w,AGT
re3,3,a1t,a2t,ACGTCA
re12,4,b1e,b2e,ACGTACT

And I want to append 'some_string' to columns 3 and 4:

re1,1,some_stringa1e,some_stringa2e,AGT
re2,2,some_stringa1w,some_stringa2w,AGT
re3,3,some_stringa1t,some_stringa2t,ACGTCA
re12,4,some_stringb1e,some_stringb2e,ACGTACT

I was trying something similar to the suggestion solution, but to no avail:

awk -v OFS=$'\,' '{ $3="some_string" $3; print}' $lookup_file

Also, I would like my string to be added to both columns. How would you do this with awk or bash?

Thanks a lot in advance

Upvotes: 0

Views: 1744

Answers (3)

vintnes
vintnes

Reputation: 2030

awk's default action is to concatenate, so you can simply place strings next to each other and they'll be treated as one. 1 means true, so with no {action} it will assume "print". You can use Bash's Brace Expansion to assign multiple variables after the script.

awk '{$3 = "three" $3; $4 = "four" $4} 1' {O,}FS=,

Upvotes: 1

Barmar
Barmar

Reputation: 780655

You need to set FS to comma, not just OFS. There's a shortcut for setting FS, it's the -F option.

awk -F, -v OFS=',' '{ $3="some_string" $3; $4 = "some_string" $4; print}' "$lookup_file"

Upvotes: 1

paxdiablo
paxdiablo

Reputation: 881093

You can do that with (almost) what you have:

pax> echo 're1,1,a1e,a2e,AGT
re2,2,a1w,a2w,AGT
re3,3,a1t,a2t,ACGTCA
re12,4,b1e,b2e,ACGTACT' | awk 'BEGIN{FS=OFS=","}{$3 = "pre3:"$3; $4 = "pre4:"$4; print}'

re1,1,pre3:a1e,pre4:a2e,AGT
re2,2,pre3:a1w,pre4:a2w,AGT
re3,3,pre3:a1t,pre4:a2t,ACGTCA
re12,4,pre3:b1e,pre4:b2e,ACGTACT

The begin block sets the input and output field separators, the two assignments massage fields 3 and 4, and the print outputs the modified line.

Upvotes: 2

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