On Windows, default terminal for Atom\'s Platformio-Ide-Terminal is Powershell (at least, that is what I get without any configuration).
I would prefer a terminal using
For CYGWIN users, the bash executable from the following location has proved useful for setting the shell override Settings >> Packages >> Platformio Ide Terminal >> Settings >> Shell Override
Settings >> Packages >> Platformio Ide Terminal >> Settings >> Shell Override
C:\cygwin64\bin\bash.exe