/usr/local/sbin/i2ctransfer: invalid option -- '-'
Usage: i2ctransfer [OPTIONS] I2CBUS DESC [DATA] [DESC [DATA]]...
  OPTIONS: -a allow even reserved addresses
           -b print read data as binary, disables -v
           -f force access even if address is marked used
           -h this help text
           -v verbose mode
           -V version info
           -y yes to all confirmations
  I2CBUS is an integer or an I2C bus name
  DESC describes the transfer in the form: {r|w}LENGTH[@address]
    1) read/write-flag 2) LENGTH (range 0-65535, or '?')
    3) I2C address (use last one if omitted)
  DATA are LENGTH bytes for a write message. They can be shortened by a suffix:
    = (keep value constant until LENGTH)
    + (increase value by 1 until LENGTH)
    - (decrease value by 1 until LENGTH)
    p (use pseudo random generator until LENGTH with value as seed)

Example (bus 0, read 8 byte at offset 0x64 from EEPROM at 0x50):
  # i2ctransfer 0 w1@0x50 0x64 r8
Example (same EEPROM, at offset 0x42 write 0xff 0xfe ... 0xf0):
  # i2ctransfer 0 w17@0x50 0x42 0xff-