internal field separator

        Internal field separator （Internal Field Separator,IFS） yes shell An important concept in scripting . When processing text data , Often used .IFS In essence, it is a variable that holds the delimiter . 
        for instance , There is one CSV file , If you want to extract words ,  have access to IFS=" "; If you want to extract comma separated field values , You can use IFS="," .

extract CSV Fields in ：
 

#!/bin/bash
data="Fist name, Last name, gender, rollno, location" 

oldIFS=${IFS}
IFS=,                                                                                                                                                                                                           
for item in ${data};
do
    echo "Item : ${item}"
done

IFS=${oldIFS}

The operation results are as follows ：

 

If you put IFS=, One line removed . So the default IFS Will be blank characters . The run result will change to ：