Getting ready

Consider the case of CSV data:

data="name,gender,rollno,location" 
To read each of the item in a variable, we can use IFS. 
oldIFS=$IFS 
IFS=, # IFS is now a , 
for item in $data; 
do 
    echo Item: $item 
done 

IFS=$oldIFS

This generates the following output:

Item: name
Item: gender
Item: rollno
Item: location

The default value of IFS is a white-space (newline, tab, or a space character).

When IFS is set as , the shell interprets the comma as a delimiter character, therefore, the $item variable takes substrings separated by a comma as its value during the iteration.

If IFS is not set as , then it will print the entire data as a single string.