What is IFS variable?

The IFS (Internal Field Separator) variable in shell scripting is a special variable that defines the character(s) used by the shell to split input strings into words or fields. By default, IFS is set to whitespace characters (space, tab, and newline), which means that when the shell processes input, it uses these characters to determine where to split the input.

Key Points about IFS:

1. Default Value: The default value of IFS is:

   IFS=' \t\n'

2. Customizing IFS: You can change the value of IFS to customize how the shell splits strings. For example, if you want to split a string by commas, you can set IFS like this:

   IFS=','

3. Usage in Loops: IFS is often used in loops to process lists of items. For example:

   IFS=','  # Set IFS to comma
   for item in $MY_LIST; do
       echo "$item"
   done

   In this case, MY_LIST would be split into separate items based on commas.

4. Restoring IFS: After modifying IFS, it's a good practice to restore it to its original value to avoid unintended consequences in other parts of the script:

   OLD_IFS=$IFS  # Save the old IFS
   IFS=','       # Change IFS
   # ... your code ...
   IFS=$OLD_IFS  # Restore the old IFS

Summary:

The IFS variable is a powerful tool for controlling how the shell interprets and splits input strings. By customizing IFS, you can effectively manage how data is processed in your scripts, especially when dealing with different delimiters.