.\" Copyright (c) 2013-2026 Devin Teske <dteske@FreeBSD.org>
.\" Copyright (c) 2021-2026 Faraz Vahedi <kfv@FreeBSD.org>
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.Dd September 22, 2026
.Dt SYSCONF-TARGETS 8
.Os
.Sh NAME
.Nm sysconf-targets
.Nd sysconf multi-file sourcing and write policy
.Sh SYNOPSIS
.Nm sysconf
.Ar target
.Op options
.Op Ar name Ns Op Ns Oo +|- Oc Ns = Ns Ar value ...
.Sh DESCRIPTION
This page documents rules shared by every
.Xr sysconf 8
target that is backed by more than one configuration file.
Per-target file lists and syntax quirks are in
.Xr sysconf-loader 8 ,
.Xr sysconf-sysctl 8 ,
.Xr sysconf-make 8 ,
.Xr sysconf-src 8 ,
.Xr sysconf-rc 8 ,
.Xr sysconf-poudriere 8 ,
and
.Xr sysconf-generic 8 .
Shared options remain in
.Xr sysconf 8 .
.Ss 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.
.Pp
Reads report that authoritative value.
Writes are applied to the authoritative file
.Pq so the change survives a reboot
or appended to the target's default write file
.Pq the first modifiable file listed
when the directive is set nowhere or only in the read-only defaults.
Removals
.Pq Fl x
are applied to every file listing the directive,
lest deleting the authoritative definition merely unmask an earlier one.
.Ss Defaults files
For a target with a defaults file
.Po
presently
.Ql loader ;
see
.Xr sysconf-loader 8
.Pc ,
the boot-time consumer sources the defaults before everything else,
and so does
.Nm sysconf :
a directive no conf file mentions still reads back its default
.Pq the value that does, in fact, take effect at boot ,
with
.Fl 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
.Fl l
or
.Fl L
.Pq which enumerate only files Nm sysconf may modify .
.Pp
Those targets additionally support querying defaults:
.Fl d
reports directive descriptions,
.Fl D
consults the defaults alone,
and
.Fl A
widens dumps to include directives still at their system default
.Po
a named
.Ar name
read always reflects the defaults already;
.Fl A
changes only
.Fl a
scope,
or dumps everything when given with no
.Ar name
arguments
.Pc .
Attempting any of these against a target with no defaults
.Po
.Cm make
and
.Cm src
have neither a defaults file nor directive descriptions
.Pc
is an error.
The one exception is
.Ql sysctl -d ,
whose descriptions come from the running kernel rather than any file
.Pq see Xr sysconf-sysctl 8 .
.Ss Explicit file selection
An arbitrary configuration file may be selected with
.Fl f ,
which overrides
.Em which
file is consulted and modified
.Pq the named file alone; multi-file processing is disabled
but never
.Em how :
the format is always stated explicitly by the
.Ar target
keyword and is never inferred from the file.
This composes freely,
so a
.Xr loader.conf 5 Ns -formatted
file may be staged anywhere
.Pq Ql sysconf loader -f /tmp/loader.conf.new ...
and,
conversely,
any format may be deliberately applied to any file.
.Pp
How each built-in format discovers or lists its backing files is
implemented by
.Xr bsdconf_format 3 .
.Sh LIMITATIONS
.Nm sysconf
does not evaluate
.Xr make 1
conditionals
.Pq Ql .if , .elif , .else , .endif
or other makefile control flow that may appear in
.Pa make.conf ,
.Pa src.conf ,
or
.Pa src-env.conf .
.Pp
It also does not consult
.Pa sys.mk ,
.Pa local.sys.mk ,
or other
.Xr make 1
defaults under
.Pa /usr/share/mk .
.Pp
Effective values from
.Nm sysconf
therefore match
.Nm make Fl V
for straight-line assignment and
.Ql +=
chains in those conf files,
but may differ when the value depends on conditionals or mk defaults.
.Sh SEE ALSO
.Xr bsdconf_format 3 ,
.Xr sysconf 8 ,
.Xr sysconf-generic 8 ,
.Xr sysconf-loader 8 ,
.Xr sysconf-make 8 ,
.Xr sysconf-poudriere 8 ,
.Xr sysconf-rc 8 ,
.Xr sysconf-src 8 ,
.Xr sysconf-sysctl 8
.Sh HISTORY
The
.Nm sysconf
utility first appeared in
.Fx 16.0 .
.Sh AUTHORS
.An Devin Teske Aq Mt dteske@FreeBSD.org
.An Faraz Vahedi Aq Mt kfv@FreeBSD.org