If you have a cygwin installation, it can be a bit hard to get cl to work in cygwin. The reason is because cl.exe needs all the fancy environment variables set up to work properly. Here’s a configuration that I’ve been using for a long time.

1. Download this shell script and place it in /home/USERNAME (or just ~). I don’t remember where I got the shell script from.

2. Type this at the end of ~/.bash_profile. Of course, paths may vary. Also, note the x64 following the path. Changing it to x86 will invoke the x86 version of cl.

   pwd=`pwd`
   cd ~
   ./extractvcvars.sh "C:\\Program Files (x86)\\Microsoft Visual Studio\\2017\\Community\\VC\\Auxiliary\\Build\\vcvarsall.bat" x64 &> /dev/null
   . ./localdevenv.sh
   cd "${pwd}"
   

3. Run cygwin, and hopefully it should work? The script will generate 2 additional files every time you run cygwin. (Of course, you really need to run extractvcvars.sh once, and just use the localdevenv.sh. But it’s easier to manage this way.)