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?
asked Apr 3, 2013 at 18:39
2 Answers
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.
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.
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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. Jan 23, 2016 at 20:16
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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.– aalaapJun 6, 2016 at 10:42
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21I believe the "mumble mumble" is a soft prank to Windows users, where
CTRL+Sis the save hotkey. Welcome to Unix Nov 18, 2016 at 20:45 -
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CTRL-Sworks (as save file) in Ubuntu 18.04, but not in 16.04.