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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | EXAMPLES | SEE ALSO | COLOPHON |
SD_BUS_MESSAGE_NEW_SIGNAL(3)_bus_message_new_signalBUS_MESSAGE_NEW_SIGNAL(3)
sd_bus_message_new_signal - Create a signal message
#include <systemd/sd-bus.h>
int sd_bus_message_new_signal(sd_bus *bus, sd_bus_message **m,
const char *path,
const char *interface,
const char *member);
The sd_bus_message_new_signal() function creates a new bus message
object that encapsulates a D-Bus signal, and returns it in the m
output parameter. The signal will be sent to path path, on the
interface interface, member member. When this message is sent, no
reply is expected. See sd_bus_message_new_method_call(1) for a short
description of the meaning of the path, interface, and member
parameters.
This function returns 0 if the message object was successfully
created, and a negative errno-style error code otherwise.
Errors
Returned errors may indicate the following problems:
-EINVAL
The output parameter m is NULL.
The path parameter is not a valid D-Bus path ("/an/object/path"),
the interface parameter is not a valid D-Bus interface name
("an.interface.name"), or the member parameter is not a valid
D-Bus member ("Name").
-ENOTCONN
The bus parameter bus is NULL or the bus is not connected.
-ENOMEM
Memory allocation failed.
These APIs are implemented as a shared library, which can be compiled
and linked to with the libsystemd pkg-config(1) file.
Example 1. Send a simple signal
#include <systemd/sd-bus.h>
#define _cleanup_(f) __attribute__((cleanup(f)))
int send_unit_files_changed(sd_bus *bus) {
_cleanup_(sd_bus_message_unrefp) sd_bus_message *message = NULL;
int r;
r = sd_bus_message_new_signal(bus, &message,
"/org/freedesktop/systemd1",
"org.freedesktop.systemd1.Manager",
"UnitFilesChanged");
if (r < 0)
return r;
return sd_bus_send(bus, message, NULL);
}
This function in systemd sources is used to emit the
"UnitFilesChanged" signal when the unit files have been changed.
systemd(1), sd-bus(3), sd_bus_emit_signal(3)
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
systemd 246 SD_BUS_MESSAGE_NEW_SIGNAL(3)
Pages that refer to this page: sd-bus(3) , sd_bus_emit_interfaces_added(3) , sd_bus_emit_interfaces_added_strv(3) , sd_bus_emit_interfaces_removed(3) , sd_bus_emit_interfaces_removed_strv(3) , sd_bus_emit_object_added(3) , sd_bus_emit_object_removed(3) , sd_bus_emit_properties_changed(3) , sd_bus_emit_properties_changed_strv(3) , sd_bus_emit_signal(3) , sd_bus_emit_signalv(3) , sd_bus_message_get_bus(3) , sd_bus_message_get_creds(3) , sd_bus_message_get_errno(3) , sd_bus_message_get_error(3) , sd_bus_message_get_type(3) , sd_bus_message_is_method_call(3) , sd_bus_message_is_method_error(3) , sd_bus_message_is_signal(3) , sd_bus_message_method_call(3) , SD_BUS_MESSAGE_METHOD_CALL(3) , sd_bus_message_method_error(3) , SD_BUS_MESSAGE_METHOD_ERROR(3) , sd_bus_message_method_return(3) , SD_BUS_MESSAGE_METHOD_RETURN(3) , sd_bus_message_new(3) , sd_bus_message_ref(3) , sd_bus_message_signal(3) , SD_BUS_MESSAGE_SIGNAL(3) , sd_bus_message_unref(3) , sd_bus_message_unrefp(3) , 30-systemd-environment-d-generator(7) , systemd.directives(7) , systemd.index(7)