systemd/man/sysctl.d.5
2014-07-11 02:23:25 +02:00

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.TH "SYSCTL\&.D" "5" "" "systemd 214" "sysctl.d"
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.SH "NAME"
sysctl.d \- Configure kernel parameters at boot
.SH "SYNOPSIS"
.PP
/etc/sysctl\&.d/*\&.conf
.PP
/run/sysctl\&.d/*\&.conf
.PP
/usr/lib/sysctl\&.d/*\&.conf
.SH "DESCRIPTION"
.PP
At boot,
\fBsystemd-sysctl.service\fR(8)
reads configuration files from the above directories to configure
\fBsysctl\fR(8)
kernel parameters\&.
.SH "CONFIGURATION FORMAT"
.PP
The configuration files contain a list of variable assignments, separated by newlines\&. Empty lines and lines whose first non\-whitespace character is
"#"
or
";"
are ignored\&.
.PP
Note that either
"/"
or
"\&."
may be used as separators within sysctl variable names\&. If the first separator is a slash, remaining slashes and dots are left intact\&. If the first separator is a dot, dots and slashes are interchanged\&.
"kernel\&.domainname=foo"
and
"kernel/domainname=foo"
are equivalent and will cause
"foo"
to be written to
/proc/sys/kernel/domainname\&. Either
"net\&.ipv4\&.conf\&.enp3s0/200\&.forwarding"
or
"net/ipv4/conf/enp3s0\&.200/forwarding"
may be used to refer to
/proc/sys/net/ipv4/conf/enp3s0\&.200/forwarding\&.
.PP
Each configuration file shall be named in the style of
\fIprogram\fR\&.conf\&. Files in
/etc/
override files with the same name in
/usr/lib/
and
/run/\&. Files in
/run/
override files with the same name in
/usr/lib/\&. Packages should install their configuration files in
/usr/lib/\&. Files in
/etc/
are reserved for the local administrator, who may use this logic to override the configuration files installed by vendor packages\&. All configuration files are sorted by their filename in lexicographic order, regardless of which of the directories they reside in\&. If multiple files specify the same variable name, the entry in the file with the lexicographically latest name will be applied\&. It is recommended to prefix all filenames with a two\-digit number and a dash, to simplify the ordering of the files\&.
.PP
If the administrator wants to disable a configuration file supplied by the vendor, the recommended way is to place a symlink to
/dev/null
in
/etc/sysctl\&.d/
bearing the same filename\&.
.PP
The settings configured with
sysctl\&.d
files will be applied early on boot\&. The network interface\-specific options will also be applied individually for each network interface as it shows up in the system\&. (More specifically,
net\&.ipv4\&.conf\&.*,
net\&.ipv6\&.conf\&.*,
net\&.ipv4\&.neigh\&.*
and
net\&.ipv6\&.neigh\&.*)
.SH "EXAMPLE"
.PP
\fBExample\ \&1.\ \&/etc/sysctl.d/domain-name.conf example:\fR
.sp
.if n \{\
.RS 4
.\}
.nf
# Set kernel YP domain name
kernel\&.domainname=example\&.com
.fi
.if n \{\
.RE
.\}
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1),
\fBsystemd-sysctl.service\fR(8),
\fBsystemd-delta\fR(1),
\fBsysctl\fR(8),
\fBsysctl.conf\fR(5)