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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |NOTES |HISTORY |SEE ALSO |COLOPHON | |
SD_BUS_REQUEST_NAME(3) sd_bus_request_nameSD_BUS_REQUEST_NAME(3)sd_bus_request_name, sd_bus_request_name_async, sd_bus_release_name, sd_bus_release_name_async - Request or release a well-known service name on a bus
#include <systemd/sd-bus.h>typedef int (*sd_bus_message_handler_t)(sd_bus_message *m,void *userdata,sd_bus_error *ret_error);int sd_bus_request_name(sd_bus *bus, const char *name,uint64_tflags);int sd_bus_request_name_async(sd_bus *bus, sd_bus_slot **slot,const char *name, uint64_tflags,sd_bus_message_handler_tcallback,void *userdata);int sd_bus_release_name(sd_bus *bus, const char *name);int sd_bus_release_name_async(sd_bus *bus, sd_bus_slot **slot,const char *name,sd_bus_message_handler_tcallback,void *userdata);
sd_bus_request_name()requests a well-known service name on a bus. It takes a bus connection, a valid bus name, and a flags parameter. The flags parameter is a combination of zero or more of the following flags:SD_BUS_NAME_ALLOW_REPLACEMENT After acquiring the name successfully, permit other peers to take over the name when they try to acquire it with theSD_BUS_NAME_REPLACE_EXISTINGflag set. IfSD_BUS_NAME_ALLOW_REPLACEMENTis not set on the original request, such a request by other peers will be denied. Added in version 209.SD_BUS_NAME_REPLACE_EXISTING Take over the name if it was already acquired by another peer, and that other peer has permitted takeover by settingSD_BUS_NAME_ALLOW_REPLACEMENTwhile acquiring it. Added in version 209.SD_BUS_NAME_QUEUE Queue the acquisition of the name when the name is already taken. Added in version 209.sd_bus_request_name()operates in a synchronous fashion: a message requesting the name is sent to the bus broker, and the call waits until the broker responds.sd_bus_request_name_async()is an asynchronous version ofsd_bus_request_name(). Instead of waiting for the request to complete, the request message is enqueued. The specifiedcallback will be called when the broker's response is received. If the parameter is specified asNULLa default implementation is used instead which will terminate the connection when the name cannot be acquired. The function returns a slot object in itsslot parameter — if it is passed as non-NULL— which may be used as a reference to the name request operation. Usesd_bus_slot_unref(3) to destroy this reference. Note that destroying the reference will not unregister the name, but simply ensure the specified callback is no longer called.sd_bus_release_name()releases an acquired well-known name. It takes a bus connection and a valid bus name as parameters. This function operates synchronously, sending a release request message to the bus broker and waiting for it to reply.sd_bus_release_name_async()is an asynchronous version ofsd_bus_release_name(). The specifiedcallback function is called when the name has been released successfully. If specified asNULL a generic implementation is used that ignores the result of the operation. As above, theslot (if non-NULL) is set to an object that may be used to reference the operation. These functions are supported only on bus connections, i.e. connections to a bus broker and not on direct connections.
On success, these calls return 0 or a positive integer. On failure, these calls return a negative errno-style error code. IfSD_BUS_NAME_QUEUEis specified,sd_bus_request_name()will return 0 when the name is already taken by another peer and the client has been added to the queue for the name. In that case, the caller can subscribe to "NameOwnerChanged" signals to be notified when the name is successfully acquired.sd_bus_request_name() returns > 0 when the name has immediately been acquired successfully.Errors Returned errors may indicate the following problems:-EALREADY The caller already is the owner of the specified name.-EEXIST The name has already been acquired by a different peer, and SD_BUS_NAME_REPLACE_EXISTING was not specified or the other peer did not specify SD_BUS_NAME_ALLOW_REPLACEMENT while acquiring the name.-ESRCH It was attempted to release a name that is currently not registered on the bus.-EADDRINUSE It was attempted to release a name that is owned by a different peer on the bus.-EINVAL A specified parameter is invalid. This is also generated when the requested name is a special service name reserved by the D-Bus specification, or when the operation is requested on a connection that does not refer to a bus.-ENOTCONN The bus connection has been disconnected.-ECHILD The bus connection has been created in a different process than the current one.
Functions described here are available as a shared library, which can be compiled against and linked to with thelibsystemd pkg-config(1) file. The code described here usesgetenv(3), which is declared to be not multi-thread-safe. This means that the code calling the functions described here must not callsetenv(3) from a parallel thread. It is recommended to only do calls tosetenv()from an early phase of the program when no other threads have been started.
sd_bus_request_name()andsd_bus_release_name()were added in version 209.sd_bus_request_name_async()andsd_bus_release_name_async()were added in version 237.
systemd(1),sd-bus(3),sd_bus_new(3),sd_bus_slot_unref(3)
This page is part of thesystemd (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 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-08-11.) 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 isnot part of the original manual page), send a mail to man-pages@man7.orgsystemd 258~rc2SD_BUS_REQUEST_NAME(3)Pages that refer to this page:sd-bus(3), sd_bus_set_watch_bind(3), systemd.directives(7), systemd.index(7)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |