bash $ for d in sda sdb sdc sdd sde sdf sdg; do smartctl -a /dev/$d | g
ep -i power_on_hours ; done
  9 Power_On_Hours          0x0032   061   061   000    Old_age   Alway
       -       28926
  9 Power_On_Hours          0x0032   066   066   000    Old_age   Alway
       -       25185
  9 Power_On_Hours          0x0032   094   094   000    Old_age   Alway
       -       4972
  9 Power_On_Hours          0x0012   096   096   000    Old_age   Alway
       -       31015
  9 Power_On_Hours          0x0032   097   097   000    Old_age   Alway
       -       2343
  9 Power_On_Hours          0x0012   100   100   000    Old_age   Alway
       -       3638
  9 Power_On_Hours          0x0032   097   097   000    Old_age   Alway
       -       3402