<orderedlist>
<listitem><para>Close all open file
- descriptors except stdin, stdout,
- stderr (i.e. the first three file
+ descriptors except standard input, output,
+ and error (i.e. the first three file
descriptors 0, 1, 2). This ensures
that no accidentally passed file
descriptor stays around in the daemon
write the daemon PID (as returned by
<function>getpid()</function>) to a
PID file, for example
- <filename>/var/run/foobar.pid</filename>
+ <filename>/run/foobar.pid</filename>
(for a hypothetical daemon "foobar")
to ensure that the daemon cannot be
started more than once. This must be
it is verified at the same time that
the PID previously stored in the PID
file no longer exists or belongs to a
- foreign process. Commonly, some kind of
- file locking is employed to implement
- this logic.</para></listitem>
+ foreign process.</para></listitem>
<listitem><para>In the daemon process,
drop privileges, if possible and
detect service errors and problems. It
is recommended to follow the exit code
scheme as defined in the <ulink
- url="http://refspecs.freestandards.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/iniscrptact.html">LSB
+ url="http://refspecs.linuxbase.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/iniscrptact.html">LSB
recommendations for SysV init
scripts</ulink>.</para></listitem>
interface.</para></listitem>
<listitem><para>Instead of using the
- <function>syslog()</function> call to log directly to the
- system syslog service, a new-style daemon may
- choose to simply log to standard error via
- <function>fprintf()</function>, which is then forwarded to
- syslog by the init system. If log
- priorities are necessary, these can be
- encoded by prefixing individual log
- lines with strings like "<4>"
- (for log priority 4 "WARNING" in the
- syslog priority scheme), following a
- similar style as the Linux kernel's
- <function>printk()</function> priority system. In fact,
- using this style of logging also
- enables the init system to optionally
- direct all application logging to the
- kernel log buffer (kmsg), as
- accessible via
- <citerefentry><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>. This
- kind of logging may be enabled by
- setting
- <varname>StandardError=syslog</varname>
- in the service unit file. For details,
- see
+ <function>syslog()</function> call to
+ log directly to the system syslog
+ service, a new-style daemon may choose
+ to simply log to standard error via
+ <function>fprintf()</function>, which
+ is then forwarded to syslog by the
+ init system. If log priorities are
+ necessary, these can be encoded by
+ prefixing individual log lines with
+ strings like "<4>" (for log
+ priority 4 "WARNING" in the syslog
+ priority scheme), following a similar
+ style as the Linux kernel's
+ <function>printk()</function> priority
+ system. For details, see
<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
<para>These recommendations are similar but
not identical to the <ulink
- url="http://developer.apple.com/mac/library/documentation/MacOSX/Conceptual/BPSystemStartup/Articles/LaunchOnDemandDaemons.html#//apple_ref/doc/uid/TP40001762-104738">Apple
+ url="https://developer.apple.com/library/mac/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/CreatingLaunchdJobs.html">Apple
MacOS X Daemon Requirements</ulink>.</para>
</refsect2>
exclusively on boot (and manually by the
administrator) via SysV init scripts, as
detailed in the <ulink
- url="http://refspecs.freestandards.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/iniscrptact.html">LSB
+ url="http://refspecs.linuxbase.org/LSB_3.1.1/LSB-Core-generic/LSB-Core-generic/iniscrptact.html">LSB
Linux Standard Base Core
Specification</ulink>. This method of
activation is supported ubiquitously on Linux
boot.</para>
<para>Packages using
- <citerefentry><refentrytitle>autoconf</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ <citerefentry project='die-net'><refentrytitle>autoconf</refentrytitle><manvolnum>1</manvolnum></citerefentry>
are recommended to use a configure script
excerpt like the following to determine the
unit installation path during source
work, it is recommended to add the following
to the top-level <filename>Makefile.am</filename>
file in
- <citerefentry><refentrytitle>automake</refentrytitle><manvolnum>1</manvolnum></citerefentry>-based
+ <citerefentry project='die-net'><refentrytitle>automake</refentrytitle><manvolnum>1</manvolnum></citerefentry>-based
projects:</para>
<programlisting>DISTCHECK_CONFIGURE_FLAGS = \
endif</programlisting>
<para>In the
- <citerefentry><refentrytitle>rpm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ <citerefentry project='die-net'><refentrytitle>rpm</refentrytitle><manvolnum>8</manvolnum></citerefentry>
<filename>.spec</filename> file, use snippets
like the following to enable/disable the
service during
</orderedlist>
</refsect1>
+ <refsect1>
+ <title>Placing Daemon Data</title>
+
+ <para>It is recommended to follow the general
+ guidelines for placing package files, as discussed in
+ <citerefentry><refentrytitle>file-hierarchy</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+ </refsect1>
+
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>file-hierarchy</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff