Issue with mintty: title not updated when background process exists

Thomas Wolff
Wed Apr 1 21:54:04 GMT 2020

Am 01.04.2020 um 22:21 schrieb Luc Henninger:
> Le 01/04/2020 à 14:24, Thomas Wolff a écrit :
>> Am 01.04.2020 um 14:20 schrieb Thomas Wolff:
>>> Am 01.04.2020 um 13:07 schrieb Luc Henninger:
>>>> Hello,
>>>> I have defined the PS1 variable as follow
>>>> PS1='\[\e]0;\w\a\]\[\e[32m\]\u@\h \[\e[35m\]\w\[\e[0m\]\n\$ '
>>>> so that the cur dir is set as title of the window.
>>>> This generally work for both mintty or cmd.
>>>> But after the sequence
>>>>   Luc@Mulan ~
>>>>   $ emacs &
>>>>   [1] 371
>>>>   Luc@Mulan ~
>>>>   $ cd bin
>>>>   Luc@Mulan ~/bin
>>>>   $
>>>> the title of the mintty widow remain to "~".
>>>> The same sequence with cmd window change the title to "~/bin"
>>>> The title is correctly updated only after I close emacs and push a 
>>>> return to the main window.
>>>> Any explanation? Thanks
>>> Noted first, this is in any case not a mintty issue as mintty 
>>> updates the title whenever it receives the respective escape 
>>> sequence. The scenario sounds weird, however. Is the background 
>>> process continuously sending title escape sequences? But 'emacs &' 
>>> looks like you're starting a GUI instance of emacs, right? So why 
>>> should it?
>> Try to isolate the background instance from the terminal:
>> emacs > /dev/null 2>&1 &
> Even if your proposal solve the issue, I have a question of what's 
> append in the two different cases.
> I use the same sequence (1/ cd ztry 2/ launch emacs ("emacs &" or 
> "emacs > /dev/null 2>&1 &" 3/ cd .. 4/ exit emacs 5/ newline 6/ ^D) 
> with mintty configure for logs.
> The log for the first case (mintty1459.log) is strongly longer that 
> the second one (mintty1470.log). It look like the wall window content 
> is rewritten each time a line is added.
> I would appreciate if someone can give me some explanation. It look 
> like that I have the same kind of behavior with other program (i.e. 
> scala repl or sbt)
It seems to be the magic of the ConPTY handling (either on cygwin side 
or on Windows side) to replay the title escape sequence after the 
program has been sent to the background. Your log does not yet reveal 
the whole story, though:
Is it repeatedly only initially (as seen two lines below "emacs &") or 
more often as might be assumed by your symptom description?

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