SYSTEMD.SYNTAX(7)                systemd.syntax                SYSTEMD.SYNTAX(7)

       systemd.syntax - General syntax of systemd configuration files

       This page describes the basic principles of configuration files used by
       systemd(1) and related programs for:

       •   systemd unit files, see systemd.unit(5), systemd.service(5),
           systemd.socket(5), systemd.device(5), systemd.mount(5),
           systemd.automount(5), systemd.swap(5),,
           systemd.path(5), systemd.timer(5), systemd.slice(5),
           systemd.scope(5), systemd.nspawn(5)

       •   link files, see

       •   netdev and network files, see systemd.netdev(5),

       •   daemon config files, see systemd-system.conf(5), systemd-
           user.conf(5), logind.conf(5), journald.conf(5), journal-
           remote.conf(5), journal-upload.conf(5), systemd-sleep.conf(5),

       The syntax is inspired by XDG Desktop Entry Specification[1] .desktop
       files, which are in turn inspired by Microsoft Windows .ini files.

       Each file is a plain text file divided into sections, with configuration
       entries in the style key=value. Whitespace immediately before or after
       the "=" is ignored. Empty lines and lines starting with "#" or ";" are
       ignored, which may be used for commenting.

       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.

       Example 1.

           [Section A]
           KeyOne=value 1
           KeyTwo=value 2

           # a comment

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

           [Section C]
           KeyThree=value 3\
           # this line is ignored
           ; this line is ignored too
                  value 3 continued

       Boolean arguments used in configuration files can be written in various
       formats. For positive settings the strings 1, yes, true and on are
       equivalent. For negative settings, the strings 0, no, false and off are

       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 systemd.time(7).

       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.


        1. XDG Desktop Entry Specification

systemd 247                                                    SYSTEMD.SYNTAX(7)