/home/ricmoo> ethers --account public-mnemonic.txt --mnemonic-password
Password (mnemonic): ******
network: homestead (chainId: 1)
homestead> accounts[0].getAddress()
<Promise id=0 resolved>
'0x6d3F723EC1B73141AA4aC248c3ab34A5a1DAD776'
homestead>