shell:Symbol "shell_setup" not found
Won't work on Windows.
popen is a replacement for shell on Windows. It invokes the cmd.exe shell for 'DOS' functions and you can call cygwin by doing /cygwin/bin/ls.exe or install the SFU to have some Unix in the cmd.exe path. The biggest annoyances are the windows it opens and the length of time it takes to execute even the simplest commands.