---
name: "sysctl.conf"
section: "5"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd", "openbsd", "macos"]
url: "https://new.carta.tech/sysctl.conf"
---

# sysctl.conf(5)

kernel state defaults

## 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)](/sysctl/8.md) 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)](/rc.subr/8.md) 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)](/rc/8.md) script which processes **sysctl.conf** early on in the process of transitioning to multi-user mode.

- */etc/rc.d/sysctl\_lastload*

  [rc(8)](/rc/8.md) script which processes **sysctl.conf** shortly before the system reaches the multi-user mode.

- */etc/sysctl.conf*

  Initial settings for [sysctl(8)](/sysctl/8.md).

- */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)](/rc.subr/8.md).

## 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.conf/5.md), [rc(8)](/rc/8.md), [sysctl(8)](/sysctl/8.md)

## 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)](/rcorder/8.md) to learn more about the ordering of [rc(8)](/rc/8.md) scripts.