sysctl meanings.

Chuck Swiger cswiger at
Thu Sep 16 16:29:11 PDT 2004

Lewis Thompson wrote:
> I wonder if there is a comprehensive list of what many of the sysctl
> values are, both in terms of what the node (by this I mean, say,
> hw.acpi.verbose) means, and what the values would mean/do?

'sysctl -d -a hw' will give a one-line description for many of the sysctls, 
and it's not uncommon for manpages to provide more details-- more often for 
manpages in section 4 and 8, ie, things like device drivers.

'sysctl -a' is not comprehensive since it doesn't include references to kernel 
options (or modules) which have not been enabled, but it's close.  To do 
better then that, look at the sources under /usr/src/sys.

>   If this doesn't exist would it be worth creating a website with a list
> of all these?  I've got some spare time in the next couple of days and I
> could whip something up in PHP that would hopefully do the job.

If doing this would please you, by all means: it would be somewhat useful. :-)

However, you might find that submitting src patches to add descriptions to the 
rest of the sysctls and/or clarify existing descriptions if they are too short 
or not informative would be more useful.

Also, you might give a thought to writing this stuff up in DocBook and 
submitting it to become part of the FreeBSD documentation, rather than rolling 
your own site.  I suspect that people are more likely to help keep "real" docs 
up-to-date, but YMMV....


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