I am trying to read a csv file using shell script,using the following command.
cat file.csv | while read -r a b c d e f; do echo "$a:$b:$c:$d:$e:$f"; done
When i run this command the first column in the file is not being read properly.
For Ex: If 1 st column contents are
number1,
number2,
number3,
number4,
(so on)
It outputs:
::::er1,
::::er2,
::::er3,
::::er4,
some characters are replaced by ':' this happens only for the first column contents. Where am i going wrong?
The problem is due to most likely a couple of issues:-
IFS=,csv file might likely have carriage returns(\r) which could mangle how read command processes the input stream.To remove the carriage returns(\r) use tr -d '\r' < oldFile.csv > newFile.csv and in the new file do the parsing as mentioned below.
Without setting the Internal Field Separator (IFS=","), while reading from the input stream read doesn't know where to delimit your words. Add the same in the command as below.
cat file.csv | while IFS="," read -r a b c d e f; do echo "$a:$b:$c:$d:$e:$f"; done
You can see it working as below. I have the contents of the file.csv as follows.
$ cat file.csv
abc,def,ghi,ijk,lmn,opz
1,2,3,4,5,6
$ cat file.csv | while IFS="," read -r a b c d e f; do echo "$a:$b:$c:$d:$e:$f"; done
abc:def:ghi:ijk:lmn:opz
1:2:3:4:5:6
More over using cat and looping it over it is not recommended and bash enthusiasts often call it as UUOC - Useless Use Of Cat
You can avoid this by doing
#!/bin/bash
while IFS="," read -r a b c d e f;
do
echo "$a:$b:$c:$d:$e:$f"
done < file.csv
IFScausing the issue here?