Why does Ctrl+C in a terminal interrupt instead of copying?

Question

Weirdo · Accepted Answer

In a terminal, Ctrl+C interrupts: with ISIG on, the INTR character — typically Ctrl-C, listed as 003 / ETX in the Linux termios manual — makes the driver send SIGINT to the foreground process group and discards the character. GNOME Terminal copies with Shift+Ctrl+C, or the right-click menu.

POSIX’s terminal interface is blunt: if ISIG is set, an INTR character generates SIGINT for the foreground process group and is discarded. The GNU C Library says INTR is typically C-c. Linux termios(3) lists VINTR as 003, ETX, Ctrl-C — octal 003 is ASCII End of Text. That is the line discipline at work. Highlighted text does not enter into it.

A graphical terminal has to bind copy to something that will not look like INTR. GNOME’s help is explicit: the usual Ctrl+C cannot copy or paste; use Shift+Ctrl+C, or right-click Copy. The emulator still forwards Ctrl+C to the terminal interface underneath, so interrupt arrives first.

Why does Ctrl+C in a terminal interrupt instead of copying?

The key sends INTR, not a clipboard command

Copy is the emulator’s shortcut, with Shift