ptf(7)                          (RM400 only)                         ptf(7)

NAME
     ptf - power failure and temperature checking pseudo device

DESCRIPTION
     The pseudo-device /dev/at/ptf gives the user access to the current
     state of the power and temperature sensors. The only permissible
     operations on this device are open(2) for reading, read(2), and
     close(2) with the restriction that only one open(2) can be active at
     any time. A request to open the device while it is already opened,
     will fail and errno will be set to EBUSY. If any attempt is made to
     open the device for writing, the attempt will fail and errno will be
     set to ENODEV.

     Exactly four ASCII characters are available to be read: three letters
     and a carriage return (ASCII 012) character.

     The first character describes the state of the power fail sensor: an
     uppercase "P" is returned when the main power is OK, otherwise a
     lowercase "p" is returned.

     The second character describes the state of the temperature sensor
     inside the cabinet: an uppercase "T" is returned if the temperature is
     below a critical limit (which is hardware-dependent), otherwise a
     lowercase "t" is returned.

     If the fan fails, a lowercase "f" is output, otherwise an uppercase
     "F" is returned. This is dependent on the system type.

     If the main power fails or if the temperature exceeds the critical
     limit, the driver sends a signal (SIGPWR) to the init process.

EXAMPLE
     % cat /dev/at/ptf
     PT

FILES
     /dev/at/ptf

     /sbin/powerfail.sh

SEE ALSO
     init(1M).













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