193 lines
4.1 KiB
HTML
193 lines
4.1 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of SD_BUS_MESSAGE_NEW_SIGNAL</TITLE>
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</HEAD><BODY>
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<H1>SD_BUS_MESSAGE_NEW_SIGNAL</H1>
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Section: sd_bus_message_new_signal (3)<BR>Updated: <BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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sd_bus_message_new_signal - Create a signal message
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<P>
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<B>
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</B><PRE>
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#include <<A HREF="file:///usr/include/systemd/sd-bus.h">systemd/sd-bus.h</A>>
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</PRE>
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<DL COMPACT>
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<DT id="1">
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<B>int sd_bus_message_new_signal(sd_bus *</B><I>bus</I><B>, sd_bus_message **</B><I>m</I><B>, const char *</B><I>path</I><B>, const char *</B><I>interface</I><B>, const char *</B><I>member</I><B>);</B>
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</DL>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<P>
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<DD>The
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<B>sd_bus_message_new_signal()</B>
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function creates a new bus message object that encapsulates a D-Bus signal, and returns it in the
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<I>m</I>
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output parameter. The signal will be sent to path
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<I>path</I>, on the interface
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<I>interface</I>, member
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<I>member</I>. When this message is sent, no reply is expected. See
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<B><A HREF="/cgi-bin/man/man2html?1+sd_bus_message_new_call">sd_bus_message_new_call</A></B>(1)
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for a short description of the meaning of the
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<I>path</I>,
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<I>interface</I>, and
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<I>member</I>
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parameters.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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<P>
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This function returns 0 if the message object was successfully created, and a negative errno-style error code otherwise.
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<A NAME="lbAF"> </A>
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<H3>Errors</H3>
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<P>
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Returned errors may indicate the following problems:
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<P>
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<B>-EINVAL</B>
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<DL COMPACT><DT id="2"><DD>
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The output parameter
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<I>m</I>
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is
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<B>NULL</B>.
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<P>
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The
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<I>path</I>
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parameter is not a valid D-Bus path ("/an/object/path"), the
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<I>interface</I>
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parameter is not a valid D-Bus interface name ("an.interface.name"), or the
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<I>member</I>
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parameter is not a valid D-Bus member ("Name").
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</DL>
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<P>
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<B>-ENOTCONN</B>
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<DL COMPACT><DT id="3"><DD>
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The bus parameter
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<I>bus</I>
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is
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<B>NULL</B>
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or the bus is not connected.
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</DL>
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<P>
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<B>-ENOMEM</B>
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<DL COMPACT><DT id="4"><DD>
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Memory allocation failed.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>NOTES</H2>
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<P>
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These APIs are implemented as a shared library, which can be compiled and linked to with the
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<B>libsystemd</B> <B><A HREF="/cgi-bin/man/man2html?1+pkg-config">pkg-config</A></B>(1)
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file.
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<A NAME="lbAH"> </A>
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<H2>EXAMPLES</H2>
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<P>
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<B>Example 1. Send a simple signal</B>
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<P>
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<DL COMPACT><DT id="5"><DD>
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<PRE>
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#include <<A HREF="file:///usr/include/systemd/sd-bus.h">systemd/sd-bus.h</A>>
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#define _cleanup_(f) __attribute__((cleanup(f)))
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int send_unit_files_changed(sd_bus *bus) {
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_cleanup_(sd_bus_message_unrefp) sd_bus_message *message = NULL;
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int r;
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r = sd_bus_message_new_signal(bus, &message,
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"/org/freedesktop/systemd1",
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"org.freedesktop.systemd1.Manager",
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"UnitFilesChanged");
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if (r < 0)
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return r;
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return sd_bus_send(bus, message, NULL);
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}
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</PRE>
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</DL>
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<P>
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This function in systemd sources is used to emit the
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"UnitFilesChanged"
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signal when the unit files have been changed.
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<P>
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<B><A HREF="/cgi-bin/man/man2html?1+systemd">systemd</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?3+sd-bus">sd-bus</A></B>(3)
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="6"><A HREF="#lbAB">NAME</A><DD>
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<DT id="7"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="8"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="9"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DL>
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<DT id="10"><A HREF="#lbAF">Errors</A><DD>
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</DL>
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<DT id="11"><A HREF="#lbAG">NOTES</A><DD>
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<DT id="12"><A HREF="#lbAH">EXAMPLES</A><DD>
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<DT id="13"><A HREF="#lbAI">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:54 GMT, March 31, 2021
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</BODY>
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</HTML>
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