<para>For each of the specified
commands, the first argument must be
- an absolute and literal path to an
- executable. Optionally, if the
- absolute file name is prefixed with
- <literal>@</literal>, the second token
- will be passed as
+ an absolute path to an executable.
+ Optionally, if this file name is
+ prefixed with <literal>@</literal>,
+ the second token will be passed as
<literal>argv[0]</literal> to the
executed process, followed by the
further arguments specified. If the
<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
+ 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. </para>
+ becomes part of the same argument. C-style escapes are
+ also supported, see table below. Quotes themselves are
+ removed after parsing and escape sequences
+ substituted. In addition, a trailing backslash
+ (<literal>\</literal>) may be used to merge lines.
+ </para>
<para>This syntax is intended to be very similar to
shell syntax, but only the meta-characters and
<emphasis>other elements of shell syntax are not
supported</emphasis>.</para>
+ <para>The command to execute must an absolute path
+ name. It may contain spaces, but control characters
+ are not allowed.</para>
+
<para>The command line accepts <literal>%</literal>
specifiers as described in
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
<literal>>/dev/null</literal>,
<literal>&</literal>, <literal>;</literal>, and
<literal>/bin/ls</literal>.</para>
+
+ <table>
+ <title>C escapes supported in command lines and environment variables</title>
+ <tgroup cols='2'>
+ <colspec colname='escape' />
+ <colspec colname='meaning' />
+ <thead>
+ <row>
+ <entry>Literal</entry>
+ <entry>Actual value</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><literal>\a</literal></entry>
+ <entry>bell</entry>
+ </row>
+ <row>
+ <entry><literal>\b</literal></entry>
+ <entry>backspace</entry>
+ </row>
+ <row>
+ <entry><literal>\f</literal></entry>
+ <entry>form feed</entry>
+ </row>
+ <row>
+ <entry><literal>\n</literal></entry>
+ <entry>newline</entry>
+ </row>
+ <row>
+ <entry><literal>\r</literal></entry>
+ <entry>carriage return</entry>
+ </row>
+ <row>
+ <entry><literal>\t</literal></entry>
+ <entry>tab</entry>
+ </row>
+ <row>
+ <entry><literal>\v</literal></entry>
+ <entry>vertical tab</entry>
+ </row>
+ <row>
+ <entry><literal>\\</literal></entry>
+ <entry>backslash</entry>
+ </row>
+ <row>
+ <entry><literal>\"</literal></entry>
+ <entry>double quotation mark</entry>
+ </row>
+ <row>
+ <entry><literal>\'</literal></entry>
+ <entry>single quotation mark</entry>
+ </row>
+ <row>
+ <entry><literal>\s</literal></entry>
+ <entry>space</entry>
+ </row>
+ <row>
+ <entry><literal>\x<replaceable>xx</replaceable></literal></entry>
+ <entry>character number <replaceable>xx</replaceable> in hexadecimal encoding</entry>
+ </row>
+ <row>
+ <entry><literal>\<replaceable>nnn</replaceable></literal></entry>
+ <entry>character number <replaceable>nnn</replaceable> in octal encoding</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
</refsect1>
<refsect1>
~ianmdlvl / elogind.git / blobdiff