39

While trying to save a file out of Nano the other day, I got an error message saying "XOFF ignored, mumble mumble". I have no idea what that's supposed to mean. Any insights?

  • 1
    CTRL-S works (as save file) in Ubuntu 18.04, but not in 16.04. – nobar Apr 16 at 0:08
  • Nice catch! Looks like it was added in v2.9.0! – nathangiesbrecht Apr 16 at 16:06
33

You typed the XOFF character Ctrl-S. In a traditional terminal environment, XOFF would cause the terminal to pause it's output until you typed the XON character.

Nano ignores this because Nano is a full-screen editor, and pausing it's output is pretty much a nonsensical concept.

As to why the wording is what it is, you'd have to ask the original devs.

  • pausing its output is not nonsensical if you are using 'software flow control' from a host PC on a physical terminal and are using xoff to prevent a buffer overflow when redrawing the screen (paging down, etc). But usually that'd be handled host-side and not user-side, I suppose. – Wyatt8740 Jan 23 '16 at 20:16
  • Ironically, I mostly use CTRL-X to save and quit in one go, and that always makes me confuse the X and the XOFF bits. – aalaap Jun 6 '16 at 10:42
  • 11
    I believe the "mumble mumble" is a soft prank to Windows users, where CTRL+S is the save hotkey. Welcome to Unix – DarkCygnus Nov 18 '16 at 20:45
46

You pressed Ctrl+S instead of Ctrl+O to save the file. Ctrl+S is an old flow-control key combination to pause the transmission, and stop scrolling, of data to a terminal (internally, the code sent is called XOFF). Ctrl+Q (XON) is the complement to start transmission and resume scrolling.

Nano ignores these code since it doesn't use scrolling. The muttering is likely a result of its frustration that you didn't remember to use Ctrl+O to save.

  • 1
    I gave @Michael Kohne the correct answer, only because he was a few seconds quicker than you. I guess I reflexively had used S instead of O. Thanks though! – nathangiesbrecht Apr 3 '13 at 18:59

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