/home/ethers> ethers --account wallet.json sign-message 'Hello World'
Password (wallet.json): ******
Decrypting... 100%
Message:
  Message:        "Hello World"
  Message (hex):  0x48656c6c6f20576f726c64
Sign Message? (y/N/a) y
Signature
  Flat:   0xca3f0b32a22a5ab97ca8be7e4a36b1e81d565c6822465d769f4faa4aa24539fb122ee5649c8a37c9f5fc8446593674159e3a7b039997cd6ee697a24b787b1a161b
  r:      0xca3f0b32a22a5ab97ca8be7e4a36b1e81d565c6822465d769f4faa4aa24539fb
  s:      0x122ee5649c8a37c9f5fc8446593674159e3a7b039997cd6ee697a24b787b1a16
  vs:     0x122ee5649c8a37c9f5fc8446593674159e3a7b039997cd6ee697a24b787b1a16
  v:      27
  recid:  0