devreserv(1M) (man pages section 1M: System Administration Commands)

man pages section 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

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 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.

SunOS 5.9 Last Revised 5 Jul 1990