• CTRL+S  essentially  does XOFF, which means the terminal will accept key strokes but won’t show the output of anything.
  • It will act as if your terminal is dead when it’s certainly just waiting to be turned back on.
  • CTRL+Q to turn flow-control on (XON).
  • If you pressed a whole bunch of keys before pressing CTRL+Q,  see the output from those keystrokes
[pastacode lang=”bash” manual=”Ctrl-s%3A%20lock%20the%20SSH%20terminal.%0A%0ACtrl-q%3A%20unlock%20the%20SSH%20terminal..%0A” message=”bash code” highlight=”” provider=”manual”/]
  • Ctrl-S is scroll-lock on, and Ctrl-Q is scroll lock off. This works in a lot of places on a lot of operating systems.
  • Try this when booting or shutting down at a text screen.
  • Chances are Ctrl-S will stop the scrolling messages. When done, press Ctrl-Q to continue.
  • Ctrl-s and Ctrl-q are standard handshake protocols also refered to XOFF and XON.
  • These are software handshake characters and there are also hardware handshake protocols using CTR/RTS lines.
  • These protocols were used for modems and printers which were slower than the computer
  • Pressing Ctrl-s inside vi editor or in Linux shell freezes the shell as it locks the terminal output.
  • You  need to press Ctrl-q to resume the terminal output.
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