tunchange Command

Purpose

Updates one or more tunable stanzas in a file.

Syntax

tunchange -f Filename ( -t Stanza ( {-o Parameter[=Value]} | -D ) | -m Filename2 )

Description

The tunchange command unconditionally updates a tunable file. It can also merge a second file with the current file.
Note: No message will be displayed (even when a parameter of type bosboot is changed).

Flags

Item Description
-f Filename Name of the updated tunable file. If the name does not include the '/' (forward slash) character, it is considered to be relative to /etc/tunables.
-t Stanza Name of the stanza to update. Stanza is either schedo, vmo, ioo, no, nfso, or raso. Stanza corresponds to the name of the command which can update the parameter or parameters specified by the -o flag.
-o Parameter=Value Parameter to be set to Value. It must be valid in the Stanza specified by the -t flag and consistent with the other parameters of the file specified by the -f flag.
-D Resets all parameters of the Stanza to their default value.
-m Filename2 Merges the Filename2 file with the current Filename file.

Exit Status

Item Description
0 Changes were correctly applied.
>0 One of the following conditions caused an error:
  • The specified Filename, Filename2, or Stanza was invalid.
  • Parameter=Value was invalid for the Parameter.
  • No message was provided.

Examples

  1. To update the pacefork parameter in the /etc/tunables/nextboot file, type:
    tunchange -f nextboot -t schedo -o pacefork=10
  2. To update the pacefork parameter in the /home/mine/mytunable file, type:
    tunchange -f /home/mine/mytunable -t schedo -o pacefork=10
  3. To reset all schedo stanza parameters to their default value in the /etc/tunables/nextboot file, type:
    tunchange -f nextboot -t schedo -D
  4. To merge the /home/mine/mytunable file with the /etc/tunables/nextboot file, type:
    tunchange -f nextboot -m /home/mine/mytunable

Files

Item Description
/usr/sbin/tunchange Contains the tunchange command.
/etc/tunables/ Contains the default tunable files.