Is it possible to post data from arduino connected to the PC to remote server via serial without using the ethernet shield?
Yes but you would need to the use the PC as the middle man.
The Arduino would send the data to the PC, the PC would parse the data and then update the remote server.
You can, you just have to do a program written on php or java or whatever you want to read the data from the usb serial com and send it to the server.
I mean to upload data directly from arduino without using any external script, as the ethernet shield. So is it possible?