A issue for parsing csv file by bash script

Question

I want to parsing the following csv file:

$ cat file.csv 
11:16:16:31:67:01,123456789a123456789b123456789c123456789d123456789e
11:16:16:31:67:02,123456789a123456789b123456789c123456789d123456789e
11:16:16:31:66:FF,123456789a123456789b123456789c123456789d123456789e
11:16:16:31:67:00,123456789a123456789b123456789c123456789d123456789e

Here is my code:

$ cat read.sh 
#! /bin/sh
OLDIFS=$IFS
IFS=','
while read f1 f2; do
    echo "$f1, $f2"
done < file.csv
IFS=$OLDIFS

It seems work wells:

$ ./read.sh 
11:16:16:31:67:01, 123456789a123456789b123456789c123456789d123456789e
11:16:16:31:67:02, 123456789a123456789b123456789c123456789d123456789e
11:16:16:31:66:FF, 123456789a123456789b123456789c123456789d123456789e
11:16:16:31:67:00, 123456789a123456789b123456789c123456789d123456789e

But if I change the order of output:

from

while read f1 f2; do
    echo "$f1, $f2" # <= change order
done < file.csv

to

while read f1 f2; do
    echo "$f2, $f1"
done < file.csv

Then the output is not my expected format. I don't know why? Can someone give me a tips? Thanks.

$ ./read.sh 
, 11:16:16:31:67:01b123456789c123456789d123456789e
, 11:16:16:31:67:02b123456789c123456789d123456789e
, 11:16:16:31:66:FFb123456789c123456789d123456789e
, 11:16:16:31:67:00b123456789c123456789d123456789e

Use awk for better handling of csv files if not considering a csv parser in perl, python, php. You input may have DOS line endings i.e. \r — anubhava
– anubhava, Commented Dec 6, 2021 at 7:53

Stefano Sansone · Accepted Answer · 2021-12-06 16:02:21Z

2

After remove CR, it works well:

here is my test:

$ file file.csv 
file.csv: ASCII text, with CRLF line terminators

$ dos2unix file.csv 
dos2unix: converting file file.csv to Unix format...

$ file file.csv 
file.csv: ASCII text

and it works well:

$ ./read.sh 
123456789a123456789b123456789c123456789d123456789e, 11:16:16:31:67:01
123456789a123456789b123456789c123456789d123456789e, 11:16:16:31:67:02
123456789a123456789b123456789c123456789d123456789e, 11:16:16:31:66:FF
123456789a123456789b123456789c123456789d123456789e, 11:16:16:31:67:00

edited Dec 6, 2021 at 16:02

Stefano Sansone

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answered Dec 6, 2021 at 8:10

Andrew Lin

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