devreserv(1M)						  System Administration Commands					     devreserv(1M)

NAME

       devreserv - reserve devices for exclusive use

SYNOPSIS

       devreserv [ key [device-list...]]

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  device-list. 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.

OPERANDS

       The following operands are supported:

       device-list     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.

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

EXAMPLES

       Example 1: Reserving a Floppy Disk and a Cartridge Tape

       The following example reserves 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

       Example 2: Listing All Devices Currently Reserved

       The following example lists all devices currently reserved:

       $ devreserv
	 disk1	       2423
	 diskette1     10658
	 ctape1        10658

       Example 3: Listing All Devices Currently Reserved to a Particular Key

       The following example lists all devices currently reserved to a particular key:

       $ devreserv $key
	 diskette1
	 ctape1

EXIT STATUS

       The following exit values are returned:

       0	Successful completion.

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

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

       3	Device reservation request could not be fulfilled.

FILES

       /etc/device.tab

       /etc/devlkfile

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       devfree(1M), attributes(5)

NOTES

       The commands devreserv and devfree are used to manage the availability of devices on a system. Their use is  on a participatory	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. Devices which have been reserved  cannot be used by processes which utilize the device reservation functions until  the  reserva-
       tion  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.

SunOS 5.10							    5 Jul 1990							     devreserv(1M)