How to convert CSV file in bash?

Question

I have a file, each line of which is a list of comma separated values. For example,

1, a, b, c, d, e
2, x, y, z

Now I would like to convert it in bash as follows:

1 a
1 b
1 c
1 d
1 e
2 x
2 y
2 z

How to do it with a shell (bash) script?

Answer 1

awk -F, '{for(i=2;i<=NF;i++)print $1,$i}' temp

tested below:

> cat temp
1, a, b, c, d, e
2, x, y, z
> awk -F, '{for(i=2;i<=NF;i++)print $1,$i}' temp
1  a
1  b
1  c
1  d
1  e
2  x
2  y
2  z

Answer 2

You can split the line into tokens and put them in an array. The first element of the array will be having the number, in your case it is 1 or 2 and so on. Something like this may be :

while read line
do
    arrIN=(${line//,/ })

## make a loop and echo them
## arrIN[0] will have the initial number

done < $file

# $file is the input file you are reading