.\" Copyright (c) 1999 Chris Costello <chris@FreeBSD.org>
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.Dd June 30, 2022
.Dt SYSCTL.CONF 5
.Os
.Sh NAME
.Nm sysctl.conf
.Nd kernel state defaults
.Sh DESCRIPTION
The
.Pa /etc/sysctl.conf
file is read in when the system goes into multi-user mode to set default
settings for the kernel.
The
.Pa /etc/sysctl.conf
file is in the format of the
.Xr sysctl 8
command, i.e.,
.Bd -literal -offset indent
sysctl_mib=value
.Ed
.Pp
Comments are denoted by a
.Dq #
at the beginning of a line.
Comments can also exist at the end of a line,
as seen in the
.Sx EXAMPLES
section, below.
.Pp
For kernel modules loaded via
.Xr rc.subr 8
system,
additional module-specific settings can be applied
by adding a file in the same format named
.Pf /etc/sysctl.kld.d/<module name>.conf .
.Sh FILES
.Bl -tag -width /etc/rc.d/sysctl_lastload -compact
.It Pa /etc/rc.d/sysctl
.Xr rc 8
script which processes
.Nm
early on in the process of transitioning to multi-user mode.
.It Pa /etc/rc.d/sysctl_lastload
.Xr rc 8
script which processes
.Nm
shortly before the system reaches the multi-user mode.
.It Pa /etc/sysctl.conf
Initial settings for
.Xr sysctl 8 .
.It Pa /etc/sysctl.conf.local
Machine-specific settings for sites with a common
.Pa /etc/sysctl.conf .
.It Pa /etc/sysctl.kld.d
Module specific settings for kernel modules loaded via
.Xr rc.subr 8 .
.El
.Sh EXAMPLES
To turn off logging of programs that exit due to fatal signals you may use
a configuration like
.Bd -literal -offset indent
# Configure logging.
kern.logsigexit=0	# Do not log fatal signal exits (e.g., sig 11)
.Ed
.Sh SEE ALSO
.Xr rc.conf 5 ,
.Xr rc 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
file appeared in
.Fx 4.0 .
.Sh BUGS
If loadable kernel modules are used to introduce additional kernel
functionality and sysctls to manage that functionality,
.Nm
may be processed too early in the boot process to set those sysctls.
Please consult
.Xr rcorder 8
to learn more about the ordering of
.Xr rc 8
scripts.