Linux – Prevent the line discipline from handling control characters

control-characterslinuxterminal

When you send a control character from the terminal, for example if you pressed Ctrl+C, the line discipline will receive the byte representing this control character (which is 0x03 in the case of Ctrl+C).

Now instead of the line discipline sending the byte 0x03 to the program associated with the terminal, it will instead send it the SIGINT signal (or it will do some other action if it is a different control character).

Now is there a way to prevent the line discipline from handling control characters, so what I want is for the program associated with the terminal to receive the actual bytes representing the control characters (0x03 in our case).

Best Answer

On linux, you'd use

$ stty intr undef

on the terminal concerned. That sets the interrupt character to nothing ("undef"). To restore you would use

$ stty intr ^c

See man stty for details.

Related Solutions

Telnet send Ctrl-C

Have you tried turning off localchars in your telnet client?

bash$ telnet
telnet> toggle localchars
Won't recognize certain control characters.
telnet> open myhost

You may also be able to put this command in the ~/.telnetrc file, depending on your version of telnet.

Relations between control characters, signals and terminal

The terminal driver (part of the operating system) establishes the relationship between special characters and signals. Your terminal settings, e.g., using stty, are what it uses to decide what (if anything) to do with characters that you type. You can reassign those special characters as needed with a few caveats:

only one special character per function
only single-byte characters are used

controlC and controlD are conventional: while a few applications may hardcode these values, the terminal driver does not require that.

The terminal driver is software, not part of your terminal. For some keyboards you may find different assignments of special characters more convenient than others (and for different operating systems, a few choices of the default values for the special characters may differ).

Best Answer

Related Solutions

Telnet send Ctrl-C

Relations between control characters, signals and terminal

Related Question