Trim leading whitespace from fields in csv file in Linux

Question

I want to trim only the leading whitespaces from a csv file that looks something like this:

thing1,thing2, thing something3,thing4
thing11,thing12, thing something13,thing14
etc.

(note: I want to keep the space between thing and something3)

so my output would be like this:

thing1,thing2,thing something3,thing4
thing11,thing12,thing something13,thing14

I've tried using awk '{$1=$1};1' file and a dozen other solutions that I found with a quick google search, but those usually either freeze or just do nothing in my case.

Hope someone can help me out, cheers!

do we need to worry about trailing spaces (ie, do you need to remove trailing whitespace)? — markp-fuso, Dec 05 '21 at 16:36
I only needed to remove the leading spaces from the 3rd column, however thanks to @christian-fritz I got the solution and marked it as such. — Biver, Dec 05 '21 at 16:38
See [How to parse a CSV file in Bash?](https://stackoverflow.com/a/69514496/1765658) — F. Hauri - Give Up GitHub, Dec 05 '21 at 17:08

score 1 · Accepted Answer · answered Dec 05 '21 at 16:26

1

sed 's/,[[:blank:]]*/,/g' file

Example:

> cat test.txt 
thing1,thing2, thing something3,thing4
thing12,thing12, thing something13,thing14

> cat test.txt  | sed 's/,[[:blank:]]*/,/g'
thing1,thing2,thing something3,thing4
thing12,thing12,thing something13,thing14

answered Dec 05 '21 at 16:26

Christian Fritz

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3
42
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See [How to parse a CSV file in Bash?](https://stackoverflow.com/a/69514496/1765658) – F. Hauri - Give Up GitHub Dec 05 '21 at 17:09

dawg · Answer 2 · 2021-12-05T18:10:40.343

With:

cat file
thing1,thing2, thing something3,thing4
thing12,thing12, thing something13,thing14

In awk, you can deal with non-quoted csv and remove the trailing space like so:

awk 'BEGIN{FS=",[[:space:]]*"; OFS=","}
{$1=$1}1' file

Prints:

thing1,thing2,thing something3,thing4
thing11,thing12,thing something13,thing14

Suppose you have quoted csv and you only want to change the csv delimiters -- not the embedded commas in the quoted fields, you should use a csv parser.

Given:

cat file
thing1,thing2, thing something3,"thing4, and 5"
thing11,thing12, thing something13,thing14

The easiest csv parser at the command line is ruby:

ruby -r CSV -e 'CSV.parse($<.read).each{|l| puts l.map(&:lstrip).to_csv}' file

Prints:

thing1,thing2,thing something3,"thing4, and 5"
thing11,thing12,thing something13,thing14

score 0 · Answer 3 · answered Dec 05 '21 at 18:11

0

Also with awk you can test this:

awk 'gsub(/, */, ",") 1' file
thing1,thing2,thing something3,thing4
thing12,thing12,thing something13,thing14

answered Dec 05 '21 at 18:11

Carlos Pascual

1,106
1
5
8

Trim leading whitespace from fields in csv file in Linux

3 Answers3