Sysctl: Difference between revisions
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* /proc/sys | * /proc/sys | ||
: In Linux, the sysctl interface mechanism is also present in /proc/sys | : In Linux, the sysctl interface mechanism is also present in /proc/sys | ||
< | <syntaxhighlight lang="bash"> | ||
# readout: | # readout: | ||
cat /proc/sys/net/ipv4/ip_forward | cat /proc/sys/net/ipv4/ip_forward | ||
# change (when supported for the variable) | # change (when supported for the variable) | ||
echo "1" > /proc/sys/net/ipv4/ip_forward | echo "1" > /proc/sys/net/ipv4/ip_forward | ||
</ | </syntaxhighlight > | ||
: Some old distros did not have sysctl, and this was the main way to go for on-the-fly changes. | : Some old distros did not have sysctl, and this was the main way to go for on-the-fly changes. | ||
* {{inlinecode|sysctl}} command | * {{inlinecode|sysctl}} command | ||
< | <syntaxhighlight lang="bash"> | ||
# readout: | # readout: | ||
sysctl net.ipv4.ip_forward | sysctl net.ipv4.ip_forward | ||
# change (whensupported for the variable) | # change (whensupported for the variable) | ||
sysctl -w net.ipv4.ip_forward=1 | sysctl -w net.ipv4.ip_forward=1 | ||
</ | </syntaxhighlight > | ||
--> | --> | ||
Latest revision as of 15:52, 11 September 2023
sysctl is a *nix concept, which tweaks parameters of in-kernel systems.
Linux also exposes sysctl as a virtual file system at /proc/sys, so e.g. reading out
sysctl net.ipv4.ip_forward sysctl -w net.ipv4.ip_forward=1
can also be done like
cat /proc/sys/net/ipv4/ip_forward echo 1>/proc/sys/net/ipv4/ip_forward
There is also an on-filesystem set of files that present what should be set at boot
Best known is probably
/etc/sysctl.conf
To see what kind of parameters, see current values using:
sysctl -a