Then, if you are setting up the wallet on Linux using the commandline, you use the "restore" command line this:
electrum restore [THIS IS WHERE YOU NEED TO TYPE YOUR 12 WORD SEED MNEMONIC]
Otherwise, if you are using the GUI on Linux, then simply use "File -> New\Restore -> enter a wallet name -> Standard Wallet -> I already have a seed" and then type the 12 words in. It will recreate the same wallet as on Windows AND it will contain the private keys so you can use the "payto" command etc.