devreserv(1M)                                                 devreserv(1M)

NAME
     devreserv - reserve devices for exclusive use

SYNOPSIS
     devreserv [key [devicelist [. . .]]]

DESCRIPTION
     devreserv reserves devices for exclusive use. When the device 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 key it was reserved. When
     devreserv is invoked with only the key argument, it lists the devices
     that are currently reserved to that key.

     The arguments for this command are:

     key          Designates a unique key on which the device will be
                  reserved. The key must be a positive integer.

     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.)

EXAMPLES
     To reserve a disk drive and a tape drive:

          $ key=$$
          $ echo "The current Process ID is equal to: $key"
          The Current Process ID is equal to: 10658
          $ devreserv $key disk1 qtape1

     To list all devices currently reserved:

          $ devreserv
          disk1         2423
          disk2         10658
          qtape1        10658

     To list all devices currently reserved to a particular key:

          $ devreserv $key
          disk1
          qtape1






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devreserv(1M)                                                 devreserv(1M)

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

     0 =   Successful completion of the task.

     1 =   Command syntax incorrect, invalid option used, or internal error
           occurred.

     2 =   Device table or device reservation table could not be opened for
           reading.

     3 =   Device reservation request could not be fulfilled.

NOTES
     The commands devreserv and devfree are used to manage the availability
     of devices on a system. Their use is on a participation basis and they
     do not place any constraints on the actual access to the device. They
     serve as a centralized 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.

FILES
     /etc/devlkfile

SEE ALSO
     devfree(1M).

























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