PTY not working in Mintty

Thomas Wolff
Fri Apr 10 16:21:57 GMT 2020

Am 10.04.2020 um 14:24 schrieb Marco Atzeri via Cygwin:
> Am 10.04.2020 um 14:05 schrieb Pavel Fedin via Cygwin:
>>    Hello everyone!
>>    I have two machines in my posession: a desktop and a laptop. Both
>> machines have Windows 10 and the same up to date version of Cygwin
>> installed. The only difference is "age". The laptop is a new one, with
>> freshly installed OS and Cygwin, and the desktop is about one year old
>> and its hard drive is about 10 years old, Cygwin was installed a while
>> ago and periodically upgraded.
>>    So far, on the desktop PTY does not work. Attempt to run docker (i am
>> using Docker Desktop for Windows) causes "Terminal is not a PTY" error,
>> i have to use winpty wrapper as suggested. On the laptop everything is
>> fine, docker works in MinTTY out of the box with no need for winpty.
>>    Is there maybe some hidden setting, which got stuck somewhere in the
>> older system ? Why is PTY not working? Can anyone help me to diagnose 
>> that ?
If your desktop Windows version is a bit older, it may not yet support 
the ConPTY API, so cygwin will silently drop its own conpty support. You 
might compare the build numbers (cmd /c ver, or winver).

> Hi pavel,
> what is the setting of CYGWIN variable ?
> I suggest you to run
> "cygcheck -svr > cygcheck.out" and compare the output files
> No idea what is "Docker Desktop" but I suggest you to verify that you 
> are really running mintty with the same invocation in the two cases.

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