Could anyone please let me know how to run the Silabs IDE from command line to build projects ?
I am able to open the IDE and project by command "IDE project.wsp".
Sadly, the old IDE doesn't support building from the command line.
You could use Keil uVision, if you like. It's pretty simple, just:
UV4.exe -j0 -b <path to project file>
You can also make the output write to an output file with an additional '-o <filename>.txt'
That's what I would recommend, since Silicon Labs provides a free Keil license.
You can also build projects for Studio, but it's pretty complicated.