Commands Reference, Volume 5

tuncheck Command

Purpose

Validates a tunable file.

Syntax

tuncheck [ -r | -p ] -f Filename

Description

The tuncheck command validates a tunable file. All tunables listed in the specified file are checked for range and dependencies. If a problem is detected, a warning is issued.

There are two types of validation:

against the current context: Checks to see if Filename could be applied immediately. Tunables not listed in Filename are interpreted as current values. The checking fails if a tunable of type Incremental is listed with a smaller value than its current value; it also fails if a tunable of type Bosboot or Reboot is listed with a different value than its current value.
against the next boot context: Checks to see if Filename could be applied during a reboot, that is, if it could be a valid nextboot file. Decreasing a tunable of type Incremental is allowed. If a tunable of type Bosboot or Reboot is listed with a different value than its current value, a warning is issued but the checking does not fail.

Additionally, warnings are issued if Filename contains unknown stanzas, or unknown tunables in a known stanza. However, that does not make the checking fail.

Upon success, the AIX_level, Kernel_type and Last_validation fields in the info stanza of the checked file are updated.

Flags

-f Filename	Specifies the name of the tunable file to be checked. The name is relative to /etc/tunables.
-p	Checks Filename in both current and boot contexts. This is equivalent to running tuncheck twice, one time without any flag and one time with the -r flag.
-r	Checks Filename in a boot context.

If -p or -r are not specified, Filename is checked according to the current context.

Tuning Parameter Types

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.

Exit Status

0: Filename is valid.
>0: Filename is invalid, message have been provided.

Examples

To check whether /etc/tunables/mytunable can be applied immediately, type:
```
 tuncheck -f mytunable
```
To check whether /etc/tunables/nextboot can be applied during a reboot, type:
```
 tuncheck -r -f nextboot 
```
To check whether /etc/tunables/nextboot can be applied immediately and after a reboot, type:
```
tuncheck -p -f nextboot
```

Files

/usr/sbin/tunckeck	Contains the tuncheck command.
/etc/tunables	Contains all the tunable files.

Related Information

The schedo Command, vmo command, ioo command, no command, nfso command, tundefault command, tunrestore command, and tunsave command.

Tunables File Format in AIX 5L Version 5.2 Files Reference.

Kernel Tuning in AIX 5L Version 5.2 Performance Tools Guide and Reference.