---
name: "sysconf-targets"
section: "8"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/sysconf-targets"
---

# sysconf-targets(8)

sysconf multi-file sourcing and write policy

## NAME

**sysconf-targets** – sysconf multi-file sourcing and write policy

## SYNOPSIS

**sysconf** *target* \[options\] \[*name*\[\[+\|-\]=*value* *...*\]\]

## DESCRIPTION

This page documents rules shared by every [sysconf(8)](/sysconf/8.md) target that is backed by more than one configuration file. Per-target file lists and syntax quirks are in [sysconf-loader(8)](/sysconf-loader/8.md), [sysconf-sysctl(8)](/sysconf-sysctl/8.md), [sysconf-make(8)](/sysconf-make/8.md), [sysconf-src(8)](/sysconf-src/8.md), [sysconf-rc(8)](/sysconf-rc/8.md), [sysconf-poudriere(8)](/sysconf-poudriere/8.md), and [sysconf-generic(8)](/sysconf-generic/8.md). Shared options remain in [sysconf(8)](/sysconf/8.md).

### Authoritative file

Most targets consult several files in the deterministic order the system sources them at boot. A directive in a later file overrides the same directive in an earlier one, so the last file listing a directive is the authoritative source of its value.

Reads report that authoritative value. Writes are applied to the authoritative file (so the change survives a reboot) or appended to the target's default write file (the first modifiable file listed) when the directive is set nowhere or only in the read-only defaults. Removals (**-x**) are applied to every file listing the directive, lest deleting the authoritative definition merely unmask an earlier one.

### Defaults files

For a target with a defaults file( presently ‘loader’; see [sysconf-loader(8)](/sysconf-loader/8.md)), the boot-time consumer sources the defaults before everything else, and so does **sysconf**: a directive no conf file mentions still reads back its default (the value that does, in fact, take effect at boot), with **-F** truthfully naming the defaults file as its source. The defaults file is nevertheless read-only bookkeeping: it is never chosen as a write target, never satisfies a removal, and is never listed by **-l** or **-L** (which enumerate only files **sysconf** **may** **modify**).

Those targets additionally support querying defaults: **-d** reports directive descriptions, **-D** consults the defaults alone, and **-A** widens dumps to include directives still at their system default( a named *name* read always reflects the defaults already; **-A** changes only **-a** scope, or dumps everything when given with no *name* arguments). Attempting any of these against a target with no defaults( **make** and **src** have neither a defaults file nor directive descriptions) is an error. The one exception is ‘sysctl -d’, whose descriptions come from the running kernel rather than any file (see [sysconf-sysctl(8)](/sysconf-sysctl/8.md)).

### Explicit file selection

An arbitrary configuration file may be selected with **-f**, which overrides *which* file is consulted and modified (the named file alone; multi-file processing is disabled) but never *how*: the format is always stated explicitly by the *target* keyword and is never inferred from the file. This composes freely, so a [loader.conf(5)](/loader.conf/5.md)-formatted file may be staged anywhere (‘sysconf loader -f /tmp/loader.conf.new ...’) and, conversely, any format may be deliberately applied to any file.

How each built-in format discovers or lists its backing files is implemented by [bsdconf\_format(3)](/bsdconf_format/3.md).

## LIMITATIONS

**sysconf** does not evaluate [make(1)](/make/1.md) conditionals (‘.if, .elif, .else, .endif’) or other makefile control flow that may appear in *make.conf*, *src.conf*, or *src-env.conf*.

It also does not consult *sys.mk*, *local.sys.mk*, or other [make(1)](/make/1.md) defaults under */usr/share/mk*.

Effective values from **sysconf** therefore match **make** **-V** for straight-line assignment and ‘+=’ chains in those conf files, but may differ when the value depends on conditionals or mk defaults.

## SEE ALSO

[bsdconf\_format(3)](/bsdconf_format/3.md), [sysconf(8)](/sysconf/8.md), [sysconf-generic(8)](/sysconf-generic/8.md), [sysconf-loader(8)](/sysconf-loader/8.md), [sysconf-make(8)](/sysconf-make/8.md), [sysconf-poudriere(8)](/sysconf-poudriere/8.md), [sysconf-rc(8)](/sysconf-rc/8.md), [sysconf-src(8)](/sysconf-src/8.md), [sysconf-sysctl(8)](/sysconf-sysctl/8.md)

## HISTORY

The **sysconf** utility first appeared in FreeBSD 16.0.

## AUTHORS

Devin Teske ⟨*dteske@FreeBSD.org*⟩ Faraz Vahedi ⟨*kfv@FreeBSD.org*⟩