Documentation for /proc/sys¶
Copyright (c) 1998, 1999, Rik van Riel <riel@nl.linux.org>
‘Why’, I hear you ask, ‘would anyone even _want_ documentationfor them sysctl files? If anybody really needs it, it’s all inthe source...’
Well, this documentation is written because some people eitherdon’t know they need to tweak something, or because they don’thave the time or knowledge to read the source code.
Furthermore, the programmers who built sysctl have built it tobe actually used, not just for the fun of programming it :-)
Legal blurb:
As usual, there are two main things to consider:
you get what you pay for
it’s free
The consequences are that I won’t guarantee the correctness ofthis document, and if you come to me complaining about how youscrewed up your system because of wrong documentation, I won’tfeel sorry for you. I might even laugh at you...
But of course, if you _do_ manage to screw up your system usingonly the sysctl options used in this file, I’d like to hear ofit. Not only to have a great laugh, but also to make sure thatyou’re the last RTFMing person to screw up.
In short, e-mail your suggestions, corrections and / or horrorstories to: <riel@nl.linux.org>
Rik van Riel.
Introduction¶
Sysctl is a means of configuring certain aspects of the kernelat run-time, and the /proc/sys/ directory is there so that youdon’t even need special tools to do it!In fact, there are only four things needed to use these configfacilities:
a running Linux system
root access
common sense (this is especially hard to come by these days)
knowledge of what all those values mean
As a quick ‘ls /proc/sys’ will show, the directory consists ofseveral (arch-dependent?) subdirs. Each subdir is mainly aboutone part of the kernel, so you can do configuration on a pieceby piece basis, or just some ‘thematic frobbing’.
This documentation is about:
abi/ | execution domains & personalities |
<$ARCH> | tuning controls for various CPU architecture (e.g. csky, s390) |
crypto/ | <undocumented> |
debug/ | <undocumented> |
dev/ | device specific information (e.g. dev/cdrom/info) |
fs/ | specific filesystemsfilehandle, inode, dentry and quota tuningbinfmt_misc <Kernel Support for miscellaneous Binary Formats (binfmt_misc)> |
kernel/ | global kernel info / tuningmiscellaneous stuffsome architecture-specific controlssecurity (LSM) stuff |
net/ | networking stuff, for documentation look in:<Documentation/networking/> |
proc/ | <empty> |
sunrpc/ | SUN Remote Procedure Call (NFS) |
user/ | Per user namespace limits |
vm/ | memory management tuningbuffer and cache management |
xen/ | <undocumented> |
These are the subdirs I have on my system or have been discovered bysearching through the source code. There might be more or other subdirsin another setup. If you see another dir, I’d really like to hear aboutit :-)