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SYSCTL.CONF(5) File Formats Manual SYSCTL.CONF(5)

sysctl.confsysctl variables to set at system startup

sysctl.conf contains a list of sysctl(8) variable assignments that is read at system startup by rc(8) early on in the boot sequence.

The file is made up of sysctl(8) variable assignments (variable=value) with comments designated by a hash mark (‘#’).


To turn on IP forwarding, one would use the following line:


To cause the kernel to reboot on a panic, instead of dropping into the debugger, the following can be used:


sysctl(2), rc(8), sysctl(8)

A sysctl.conf file first appeared in OpenBSD 2.3.

February 10, 2020 OpenBSD-current