Running a console executable from a tcl script

You'll get the results you describe if your executable doesn't produce any output to STDOUT.

Your script snippet works fine here.

Changing your cmd variable to instead use Windows cmd.exe to run the "set" command, you get your environment dumped into Quartus messages.

set cmd "cmd /c set"
post_message "cmd: ${cmd}"
if {  } {
    post_message -type error "couldn't run $cmd"
} else {
    post_message -type info "Command \"$cmd\" successful."
    post_message -type info 
}

If something basic as this doesn't work for you, not sure what next? Reinstall?

If this works, then there's a problem with your .exe, or there is a problem executing your .exe from a script like this.