'\" t
.TH "SYSTEMD\&.SYNTAX" "7" "" "systemd 241" "systemd.syntax"
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.SH "NAME"
systemd.syntax \- General syntax of systemd configuration files
.SH "INTRODUCTION"
.PP
This page describes the basic principles of configuration files used by
\fBsystemd\fR(1)
and related programs for:
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
systemd unit files, see
\fBsystemd.unit\fR(5),
\fBsystemd.service\fR(5),
\fBsystemd.socket\fR(5),
\fBsystemd.device\fR(5),
\fBsystemd.mount\fR(5),
\fBsystemd.automount\fR(5),
\fBsystemd.swap\fR(5),
\fBsystemd.target\fR(5),
\fBsystemd.path\fR(5),
\fBsystemd.timer\fR(5),
\fBsystemd.slice\fR(5),
\fBsystemd.scope\fR(5)
.RE
.sp
.RS 4
.ie n \{\
\h'-04'\(bu\h'+03'\c
.\}
.el \{\
.sp -1
.IP \(bu 2.3
.\}
daemon config files, see
\fBsystemd-system.conf\fR(5),
\fBsystemd-user.conf\fR(5),
\fBlogind.conf\fR(5),
\fBjournald.conf\fR(5),
\fBjournal-remote.conf\fR(5),
\fBjournal-upload.conf\fR(5),
\fBsystemd-sleep.conf\fR(5),
\fBtimesyncd.conf\fR(5)
.RE
.PP
The syntax is inspired by
\m[blue]\fBXDG Desktop Entry Specification\fR\m[]\&\s-2\u[1]\d\s+2
\&.desktop
files, which are in turn inspired by Microsoft Windows
\&.ini
files\&.
.PP
Each file is a plain text file divided into sections, with configuration entries in the style
\fIkey\fR=\fIvalue\fR\&. Empty lines and lines starting with
"#"
or
";"
are ignored, which may be used for commenting\&.
.PP
Lines ending in a backslash are concatenated with the following line while reading and the backslash is replaced by a space character\&. This may be used to wrap long lines\&. The limit on line length is very large (currently 1 MB), but it is recommended to avoid such long lines and use multiple directives, variable substitution, or other mechanism as appropriate for the given file type\&. When a comment line or lines follow a line ending with a backslash, the comment block is ignored, so the continued line is concatenated with whatever follows the comment block\&.
.PP
\fBExample\ \&1.\ \&\fR
.sp
.if n \{\
.RS 4
.\}
.nf
[Section A]
KeyOne=value 1
KeyTwo=value 2

# a comment

[Section B]
Setting="something" "some thing" "\&..."
KeyTwo=value 2 \e
       value 2 continued

[Section C]
KeyThree=value 2\e
# this line is ignored
; this line is ignored too
       value 2 continued
.fi
.if n \{\
.RE
.\}
.PP
Boolean arguments used in configuration files can be written in various formats\&. For positive settings the strings
\fB1\fR,
\fByes\fR,
\fBtrue\fR
and
\fBon\fR
are equivalent\&. For negative settings, the strings
\fB0\fR,
\fBno\fR,
\fBfalse\fR
and
\fBoff\fR
are equivalent\&.
.PP
Time span values encoded in configuration files can be written in various formats\&. A stand\-alone number specifies a time in seconds\&. If suffixed with a time unit, the unit is honored\&. A concatenation of multiple values with units is supported, in which case the values are added up\&. Example:
"50"
refers to 50 seconds;
"2min\ \&200ms"
refers to 2 minutes and 200 milliseconds, i\&.e\&. 120200\ \&ms\&. The following time units are understood:
"s",
"min",
"h",
"d",
"w",
"ms",
"us"\&. For details see
\fBsystemd.time\fR(7)\&.
.PP
Various settings are allowed to be specified more than once, in which case the interpretation depends on the setting\&. Often, multiple settings form a list, and setting to an empty value "resets", which means that previous assignments are ignored\&. When this is allowed, it is mentioned in the description of the setting\&. Note that using multiple assignments to the same value makes the file incompatible with parsers for the XDG
\&.desktop
file format\&.
.SH "SEE ALSO"
.PP
\fBsystemd.time\fR(7)
.SH "NOTES"
.IP " 1." 4
XDG Desktop Entry Specification
.RS 4
\%http://standards.freedesktop.org/desktop-entry-spec/latest/
.RE