SYSCTL.CONF(5)

NAME
sysctl.conf - kernel state defaults

DESCRIPTION
The /etc/sysctl.conf file is read in when the system goes into multi-user mode to set default settings for the kernel. The /etc/sysctl.conf file is in the format of the sysctl(8) command, i.e.,

    sysctl_mib=value

Comments are denoted by a “#” at the beginning of a line. Comments can also exist at the end of a line, as seen in the EXAMPLES section, below.

For kernel modules loaded via rc.subr(8) system, additional module-specific settings can be applied by adding a file in the same format named /etc/sysctl.kld.d/<modulename>.conf.

FILES
/etc/rc.d/sysctl
    rc(8) script which processes sysctl.conf early on in the process of transitioning to multi-user mode.
/etc/rc.d/sysctl_lastload
    rc(8) script which processes sysctl.conf shortly before the system reaches the multi-user mode.
/etc/sysctl.conf
    Initial settings for sysctl(8).
/etc/sysctl.conf.local
    Machine-specific settings for sites with a common /etc/sysctl.conf.
/etc/sysctl.kld.d
    Module specific settings for kernel modules loaded via rc.subr(8).

EXAMPLES
To turn off logging of programs that exit due to fatal signals you may use a configuration like

    # Configure logging.
    kern.logsigexit=0	# Do not log fatal signal exits (e.g., sig 11)

SEE ALSO
rc.conf(5), rc(8), sysctl(8)

HISTORY
The sysctl.conf file appeared in FreeBSD 4.0.

BUGS
If loadable kernel modules are used to introduce additional kernel functionality and sysctls to manage that functionality, sysctl.conf may be processed too early in the boot process to set those sysctls. Please consult rcorder(8) to learn more about the ordering of rc(8) scripts.