In some cases, developers may use a control character to delimit the data for every field in a flat file. For example, we can use ^A to delimit fields in vi editor.
[oracle@test tmp]$ vi testfile
Let's see its content.
[oracle@test tmp]$ cat testfile
As you can see, the control character ^A is invisible to the users. How did we do that?
Let's see some usually used control characters.
Control A (Ctrl-A)
To simulate a Ctrl-A (^A) character in vi editor, you should press and hold Ctrl key then stroke v then a keys subsequently.
Control C (Ctrl-C)
In the same way, to type a Ctrl-C (^C) character, you should press and hold Ctrl key then stroke v then c keys subsequently.
In other words, we use "Ctrl + v", the combination keys to simulate typing a Ctrl key. This trick does work in both bash and ksh shell.
Control M (Ctrl-M)
To remove ^M (carriage return) from text in vi editor, we use the similar way to do it.