---
name: "sd_bus_set_connected_signal"
section: "3"
platform: "linux"
package: "systemd-libs"
version: "262.1-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/sd_bus_set_connected_signal"
---

# sd\_bus\_set\_connected\_signal(3)

Control emission of local connection establishment signal on bus connections

## NAME

sd\_bus\_set\_connected\_signal, sd\_bus\_get\_connected\_signal - Control emission of local connection establishment signal on bus connections

## SYNOPSIS

```
#include <systemd/sd-bus.h>
```

**int sd\_bus\_set\_connected\_signal(sd\_bus \****bus***, int** *b***);**

**int sd\_bus\_get\_connected\_signal(sd\_bus \****bus***);**

## DESCRIPTION

**sd\_bus\_set\_connected\_signal()** may be used to control whether a local, synthetic **Connected()** signal message shall be generated and enqueued for dispatching when the connection is fully established. If the *b* parameter is zero the message is not generated (the default), otherwise it is generated.

**sd\_bus\_get\_connected\_signal()** may be used to query whether this feature is enabled. It returns zero if not, positive otherwise.

The **Connected()** signal message is generated from the "org.freedesktop.DBus.Local" service and interface, and "/org/freedesktop/DBus/Local" object path. Use [**sd\_bus\_match\_signal\_async**(3)](/sd_bus_match_signal_async/3.md) to match on this signal.

This message is particularly useful on slow transports where connections take a long time to be established. This is especially the case when [**sd\_bus\_set\_watch\_bind**(3)](/sd_bus_set_watch_bind/3.md) is used. The signal is generated when the [**sd\_bus\_is\_ready**(3)](/sd_bus_is_ready/3.md) returns positive for the first time.

The **Connected()** signal corresponds with the **Disconnected()** signal that is synthesized locally when the connection is terminated. The latter is generated unconditionally however, unlike the former which needs to be enabled explicitly before it is generated, with **sd\_bus\_set\_connected\_signal()**.

## RETURN VALUE

On success, these functions return 0 or a positive integer. On failure, they return a negative errno-style error code.

### Errors

Returned errors may indicate the following problems:

**-ECHILD**

The bus connection has been created in a different process, library or module instance.

## NOTES

Functions described here are available as a shared library, which can be compiled against and linked to with the **libsystemd** [**pkg-config**(1)](/pkg-config/1.md) file.

All functions listed here are thread-agnostic and only a single thread may operate on a given object at any given time. Different threads may access the same object at different times. Multiple independent objects may be used from different threads in parallel.

The code described here uses [**getenv**(3)](/getenv/3.md), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not call [**setenv**(3)](/setenv/3.md) from a parallel thread. It is recommended to only do calls to **setenv()** from an early phase of the program when no other threads have been started.

## HISTORY

**sd\_bus\_set\_connected\_signal()** and **sd\_bus\_get\_connected\_signal()** were added in version 237.

## SEE ALSO

[**systemd**(1)](/systemd/1.md), [**sd-bus**(3)](/sd-bus/3.md), [**sd\_bus\_match\_signal\_async**(3)](/sd_bus_match_signal_async/3.md), [**sd\_bus\_set\_watch\_bind**(3)](/sd_bus_set_watch_bind/3.md), [**sd\_bus\_is\_ready**(3)](/sd_bus_is_ready/3.md)