tunrestore Command

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Purpose

Restores tunable parameter values from a file.

Syntax

tunrestore [ -r ] -f Filename

tunrestore -R

Restriction: tunrestore -R can only be called from inittab.

Description

The tunrestore command restores all tunable parameters values stored in a file.

The tunrestore -f Filename immediately applies Filename. All tunables listed in Filename are set to the value defined in this file. Tunables not listed in Filename are kept unchanged. Tunables explicitly set to DEFAULT are set to their default value.

The tunrestore -r -f Filename applies Filename for the next boot. This is achieved by checking the specified file for inconsistencies (the equivalent of running tuncheck on it) and copying it over to /etc/tunables/nextboot. If bosboot is necessary, the user will be offered to run it.

The tunrestore -R is only used during reboot. All of the tunables that are not yet set to the value defined in the nextboot file are modified. Tunables that are not listed in the nextboot file are forced to their default value. All actions, warnings and errors are logged into the /etc/tunables/lastboot.log file. Note that when modification is made to restricted tunables, a system errlog entry is added, including the list of all tunable commands controlling the modified restricted tunables and a reference to the /etc/tunables/lastboot.log file.

Additionally, a new tunable file called /etc/tunables/lastboot is automatically generated. That file has all of the tunables listed with numerical values. The values representing default values are marked with the comment DEFAULT VALUE. The values that are different from the default values for restricted tunables are marked with the comment # RESTRICTED not at default value. The info stanza of the new tunable file includes the checksum of the /etc/tunables/lastboot.log file to make sure pairs of the lastboot/lastboot.log files can be identified.

Flags

Item	Description
-f Filename	Specifies the name of the tunable file to apply. If it does not contain the '/' (forward slash) character, the name is relative to /etc/tunables.
-r	Makes the specified file become the new nextboot file.
-R	Restores /etc/tunables/nextboot during boot process.

Tunable Parameter Types

Item	Description
Dynamic	Can be changed at any time.
Static	Can never be changed
Reboot	Can only be changed during the reboot sequence
Bosboot	Can only be changed by running bosboot and rebooting the machine
Mount	Changes made are only effective for future filesystems or directory mountings
Incremental	Can only be incremented, except at boot time.
Connect	Changes are only effective for future socket connections.

Examples

To restore all tunable values stored in /etc/tunables/mytunable, enter:
```
tunrestore -f mytunable
```
To validate /etc/tunables/mytunable and make it the new nextboot file, enter:
```
 tunrestore -r -f mytunable
```

Files

Item	Description
/usr/sbin/tunrestore	Contains the tunrestore command.
/etc/tunables	Contains tunable files.
/etc/tunables/nextboot	Contains the values to be applied during the next boot.
/etc/tunables/lastboot	Contains the values of all tunables after the last boot.
/etc/tunables/lastboot.log	Contains messages, warnings and errors emitted by tunrestore during the last boot.