Clarify cut command (#1496)

#1144

Author: bkmgit

episodes/04-pipefilter.md

@@ -549,10 +549,12 @@ For the file `animals.csv` from the previous exercise, consider the following co
 $ cut -d , -f 2 animals.csv
 ```
 
-The `cut` command is used to remove or 'cut out' certain sections of each line in the file,
-and `cut` expects the lines to be separated into columns by a <kbd>Tab</kbd> character.
-A character used in this way is called a **delimiter**.
-In the example above we use the `-d` option to specify the comma as our delimiter character.
+The `cut` command is used to select or 'cut out' certain sections of each line in the file for
+further processing while leaving the original file unchanged.
+By default, `cut` expects the lines to be separated into columns by a <kbd>Tab</kbd> character.
+A character used in this way is called a **delimiter**.  
+In the example above we use the `-d` option to specify the comma as our delimiter character
+instead of <kbd>Tab</kbd>.
 We have also used the `-f` option to specify that we want to extract the second field (column).
 This gives the following output: