shaba/systemd-stable
1
1
Fork 0
mirror of https://github.com/systemd/systemd-stable.git synced 2025-02-04 17:47:03 +03:00
Code

man: beef up ExecStart description

Browse Source 
We have lots of questions from people who assume that shell syntax works
here, so let's be very explicit what is allowed and what is not. A few
examples should also help.

http://bugs.debian.org/732156
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2013-12-14 17:21:55 -05:00
parent 5d5f8ffa07
commit ec6039bc08
1 changed files with 80 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

97
man/systemd.service.xml
View File

@ -305,9 +305,10 @@
<term><varname>ExecStart=</varname></term>
<listitem><para>Commands with their
arguments that are executed when this
service is started. The first
argument must be an absolute path
name.</para>
service is started. For each of the
specified commands, the first argument
must be an absolute and literal path
to an executable.</para>
<para>When <varname>Type</varname> is
not <option>oneshot</option>, only one
@ -332,6 +333,35 @@
prior assignments of this option will
have no effect.</para>
<para>Each command line is split on
whitespace, with the first item being
the command to execute, and the
subsequent items being the arguments.
Double quotes ("...") and single
quotes ('...') may be used, in which
case everything until the next
matching quote becomes part of the
same argument. Quotes themselves are
removed after parsing. In addition, a
trailing backslash
(<literal>\</literal>) may be used to
merge lines. This syntax is intended
to be very similar to shell syntax,
but only the meta-characters and
expansions described in the following
paragraphs are understood.
Specifically, redirection using
<literal>&lt;</literal>,
<literal>&lt;&lt;</literal>,
<literal>&gt;</literal>, and
<literal>&gt;&gt;</literal>, pipes
using <literal>|</literal>, and
running programs in the background
using <literal>&amp;</literal>
and <emphasis>other elements of shell
syntax are not supported</emphasis>.
</para>
<para>If more than one command is
specified, the commands are invoked
one by one sequentially in the order
@ -350,10 +380,11 @@
<para>The command line accepts
<literal>%</literal> specifiers as
described in
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Note
that the first argument of the command
line (i.e. the program to execute) may
not include specifiers.</para>
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
Note that the first argument of the
command line (i.e. the program to
execute) may not include
specifiers.</para>
<para>Basic environment variable
substitution is supported. Use
@ -372,9 +403,7 @@
more arguments. To pass a literal dollar sign,
use <literal>$$</literal>. Note that the first
argument (i.e. the program to execute)
may not be a variable, since it must
be a literal and absolute path
name.</para>
may not be a variable.</para>
<para>Optionally, if the absolute file
name is prefixed with
@ -402,13 +431,47 @@
<programlisting>ExecStart=/bin/sh -c 'dmesg | tac'
</programlisting>
<para>For services run by a user
instance of systemd the special
environment variable
<varname>$MANAGERPID</varname> is set
to the PID of the systemd
instance.</para>
</listitem>
<para>Only select environment variables
are set for executed commands. See
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
<para>Example:</para>
<programlisting>ExecStart=/bin/echo one ; /bin/echo "two two"
</programlisting>
<para>This will execute
<command>/bin/echo</command> two
times, each time with one argument,
<literal>one</literal> and
<literal>two two</literal>,
respectively. Since two commands are
specified
<varname>Type=oneshot</varname> must
be used.</para>
<para>Example:</para>
<programlisting>ExecStart=/bin/echo / &gt;/dev/null &amp; \; \
/bin/ls
</programlisting>
<para>This will execute
<command>/bin/echo</command> with five
arguments: <literal>/</literal>,
<literal>&gt;/dev/null</literal>,
<literal>&amp;</literal>,
<literal>;</literal>, and
<literal>/bin/ls</literal>.</para>
<para>Example:</para>
<programlisting>Environment="ONE=one" 'TWO=two two'
ExecStart=/bin/echo $ONE $TWO ${TWO}
</programlisting>
<para>This will execute
<command>/bin/echo</command> with four
arguments: <literal>one</literal>,
<literal>two</literal>,
<literal>two</literal>, and
<literal>two two</literal>.</para>
</listitem>
</varlistentry>
<varlistentry>