How do I prevent strange escape chars from appearing on prompt

Question

I am using Cygwin on windows 7 mintty 2.3.6 (x86_64-pc-cygwin)

And randomly a [28~ will appear on my prompt line. Sometimes it even appears while I am in the middle of typing a command. And often it appears even when the terminal window doesn't have focus.

This is really hard to google for, because google just sees the 28. I would appreciate suggestions on how to improve my google-fu to search for the specific sequence.

https://en.wikipedia.org/wiki/ANSI_escape_code . Have you redefined the PS1 or TERM setting ? — matzeri, May 14 '16 at 05:41

score 3 · Accepted Answer · answered Jun 16 '16 at 05:54

3

This can be caused by an application such as Caffeine, which stops your screensaver by pressing a key periodically (like F15 which has ansi sequence \[[28~) . You can stop the program or add an entry in your ~/.inputrc to ignore the sequence. in ~/.inputrc add the line:

"\e[28~":""

to remap F15 to nothing in the terminal.

answered Jun 16 '16 at 05:54

Isaac Hanson

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Perfect. This makes a lot of sense. And I had no idea that was how Caffeine was implemented. Thanks! it was driving me nuts. – jschank Jun 16 '16 at 15:00
So it was Caffeine? Nice. – Isaac Hanson Jun 16 '16 at 15:37

score 0 · Answer 2 · answered Nov 26 '20 at 16:27

For the record, there are two other ways to fix this:

Prevent F15 from being interpreted on the mintty side: Add the following line to your mintty config file (e.g. ~/.minttyrc). It tells mintty to ignore F15 by itself or with the Ctrl modifier, which does the trick for me (on my machine, it would produce ~ by itself, and with Ctrl, ;5~):
```
KeyFunctions=F15:void;C+F15:void
```
Prevent Caffeine from sending F15 by running it with the -useshift option.

How do I prevent strange escape chars from appearing on prompt

2 Answers2