Sign up ×  I have modified the value of net.core.rmem_max with
sysctl, and now I would like to set it back to its default
value.  If I reboot, net.core.rmem_max will go back to its
default value (because it is not overridden in
/etc/sysctl.conf), but can I know this value without rebooting?
Ideally I should have run sysctl net.core.rmem_max to read the
value before modifying it, but I forgot...  share|improve this
question  2 Answers 2  This is not possible in general: the
kernel does not retain the original values (at least under Linux
it doesn't, and this is probably true of other unix variants).
The value of the setting is stored in a variable; when you
change the setting, the memory containing the variable is
irreversibly updated.  For most settings, the initial value of
the variable is a constant that is determined at compile time
and stored in the kernel binary. So you could, in principle,
inspect your kernel binary to find the default value. You would
have to locate the symbol corresponding to the set