devreserv(1M)    SYSTEM ADMINISTRATION COMMANDS     devreserv(1M)



NAME
     devreserv - reserves devices for exclusive use

SYNOPSIS
     devreserv [pid [devicelist [...]]]

DESCRIPTION
     devreserv reserves devices for exclusive use.  When the dev-
     ice  is  no  longer  required,  use  devfree  to release it.
     devreserv reserves at most one device per devicelist.   Each
     list  is  searched in linear order until the first available
     device is found.  If a device cannot be reserved  from  each
     list,  the  entire  reservation  fails.   When  devreserv is
     invoked without arguments, it lists  the  devices  that  are
     currently  reserved  and shows to which pid it was reserved.
     When devreserv is invoked with only  the  pid  argument,  it
     lists  the  devices  that currently reserved to that process
     id.  The arguments for this command are:
     pid       Designates the application's process id number  on
               which the device will be reserved.

     devicelist
               Defines a list  of  devices  that  devreserv  will
               search  to  find  an  available device.  (The list
               must be formatted as  a  single  argument  to  the
               shell.)

EXAMPLE
     To reserve a floppy disk and a cartridge tape:
          $ key=$$
          $ echo "The current Process ID is equal to: $key"
          The Current Process ID is equal to: 10658
          $ devreserv $key diskette1 ctape1
     To list all devices currently reserved:
          $ devreserv
          disk1         2423
          diskette1     10658
          ctape1        10658
     To list all devices currently reserved to a particular key:
          $ devreserv $key
          diskette1
          ctape1

ERRORS
     The command will exit with one of the following values:

     0 = successful completion of the task.

     1 = command syntax incorrect, invalid option used, or inter-
         nal error occurred.

     2 = device table or device reservation table  could  not  be



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devreserv(1M)    SYSTEM ADMINISTRATION COMMANDS     devreserv(1M)



         opened for reading.

     3 = device reservation request could not be fulfilled.

FILES
     /etc/device.tab
     /etc/devlkfile

NOTES
     The commands devreserv and devfree are used  to  manage  the
     availability of devices on a system.  Their use is on a par-
     ticipatory basis and they do not place  any  constraints  on
     the  actual  access to the device.  They serve as a central-
     ized bookkeeping point for those who wish to use  them.   To
     summarize,  devices  which have been reserved cannot be used
     by processes which utilize the device reservation  functions
     until the reservation has been canceled.  However, processes
     that do not use device reservation may use a device that has
     been  reserved  since  such a process would not have checked
     for its reservation status.  The pid argument  must  be  the
     process  id of the controlling process.  This process should
     be active both when the device is reserved and  when  it  is
     freed.    When  a  process  becomes  inactive,  all  devices
     reserved to the process id are canceled by the system.

SEE ALSO
     devfree(1), devfree(3X), devreserv(3X), reservdev(3X).




























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