UPSD(8)

       upsd -- UPS monitor daemon.
      

SYNOPSIS

       /sbin/upsd  [options] serial-device | host-name
      

DESCRIPTION


       Upsd  is  a daemon process that sits in the background and
       monitors the state of the DCD and CTS lines of the  speci-
       fied  serial device.  These lines are to be connected to a
       UPS (Uninterruptible Power Supply) so  that  the  computer
       can  monitor  the state of the UPS.  The DCD line monitors
       for a power fail condition, while CTS monitors for  a  low
       battery  condition.   RTS  may  be optionally used to shut
       down the UPS, if that feature is  supported  by  the  UPS.
       CTS  and  RTS  may be left unconnected if the UPS does not
       support the corresponding features.

       Upsd can also run in slave mode.  In this mode, upsd polls
       another copy of itself running on a remote host.  This can
       be used to give a controlled shutdown capability to all of
       the  hosts  on  a  network,  even ones which do not have a
       hardwired monitor connection to the UPS.

       When upsd senses that the power is  failing,  it  notifies
       init(8),  which  will  execute the powerwait and powerfail
       entries in /etc/inittab.  If upsd senses  that  the  power
       has  been  restored,  it notifies init again and init will
       execute the powerokwait entry.

       Upsd uses the syslog(2) facility for status reporting when
       running as a daemon.
      

ARGUMENTS

       serial-device
              Some  serial port that is not being used by another
              device, and does not share an  interrupt  with  any
              other serial port.  Not valid with -s.

       host-name
              A  host  name  or IP address.  Only valid if the -s
              option is used.
      

OPTIONS

       -c count
              Wait count poll  intervals  before  shutdown.   The
              default  is  2.  This option is intended to prevent
              users on the system from being bothered  by  alerts
              caused by short power glitches.  It should probably
              be set to 0 (signal right away) on slave  machines.

       -h     Print a short usage message and exit.

              Set  the poll interval to time seconds.  Default is
              10 seconds.  This should probably be shorter on the
              master  machine  and  longer  on the slaves.  Times
              less than 0  are  interpreted  to  mean  that  upsd
              should  get  the  UPS  status  and exit immediately
              (this is useful in a "halt" script).  The UPS  sta-
              tus is returned in the exit code.

       -k     Kill  the UPS power.  Most brands of UPS will honor
              this signal only if they  are  running  on  battery
              power.  Causes RTS to go high for 5 seconds.

       -l     Don't  shut  down  until  a  low battery indication
              appears.   Should  only  be  used   on   standalone
              machines,  and  only with init set up for immediate
              shutdown.  On battery  indications  will  still  be
              logged, but won't cause a shutdown.

       -m     Disable  master mode.  Do not respond to polls from
              slave machines.  Do not listen on a TCP  port.   Do
              monitor  the UPS and signal power failures to init.
              This mode is intended for standalone machines.

       -p port
              Listen on port in master mode, try to contact  port
              for updates in slave mode.  Default is port 401.

       -s     Run in slave mode.  Poll a master host for UPS sta-
              tus.  The host name or IP replaces the device  name
              on the command line if this flag is specified.

       -t     Test  mode.   Do  not  become a daemon, do not send
              SIGPWR to init.  This mode is intended for  testing
              your setup.
      

RETURN CODES

       Normally,  upsd  does  not return status codes, because it
       does not exit.  If upsd  does  exit  abnormally,  it  will
       return  a  status  of  1.   If  killed by SIGTERM, it will
       return a status of 0.  If upsd is run with a poll interval
       (-i)  value less than zero, it will get the UPS status and
       exit.  The return codes are as follows:

       100    Power is OK.

       101    UPS is on battery, but the battery is ok.

       102    UPS is on battery, and the battery is low.

       103    There was a UPS connection error.  Cound  not  con-
              tact the host (in slave mode), or the monitor cable
              is disconnected (in master mode).

       Upsd regularly checks the DSR line to see if it  is  high.
       DSR  should  be  directly  connected to DTR and upsd keeps
       that line high, so if DSR is low then something  is  wrong
       with  the  connection.   Upsd  will  notify you about this
       fact.  When it sees that the connection has been  restored
       it will say so.
      

HOWTO

       It's pretty simple to connect your UPS to a Linux machine.
       The steps are as follows:

       1.     Make sure you have an UPS with a simple relay  out-
              put;  it should close its connections (make) if the
              power is gone, and it should open  its  connections
              (break) if the power is good.

       2.     Buy  a serial plug. Connect the DTR line to the DSR
              line directly.  Connect the DTR line  and  the  DCD
              line with a 10 kOhm resistor.  Connect the CTS line
              and the DTR line with  another  10  kOhm  resistor.
              Now connect the (normally open) ON BATTERY relay of
              the UPS to the DCD line and the (normally open) LOW
              BATTERY  relay  to  the  CTS line.  Connect the RTS
              line to the SHUTDOWN input on the UPS.  Connect the
              return side of the relays to GROUND.

       3.     You're  all set.  It is also safe to use this setup
              with a UPS having open collector outputs, like  the
              APC SmartUPS v/s series, but be very careful to not
              exceed the current limit of the output transistors.
              It  is possible, though unlikely, that you may need
              to increase the resistor values for some units.
      

FILES

       /etc/inittab
              Control file for init(8).

       /etc/powerstatus
              Power status file read by init(8)  after  receiving
              SIGPOWER.
      

BUGS

       No  way  to  specify  the  polarity of the SHUTDOWN signal
       (always goes high for shutdown).   Could  probably  handle
       connection errors better.  There's probably a standard for
       UPS monitoring on a network somewhere, but if so  I  don't
       know about it.
      

SEE ALSO

       shutdown(8), init(8), inittab(5).
      

AUTHOR

       Bob Hauck