nbd_get_uri - construct an NBD URI for a connection


 #include <libnbd.h>

 char * nbd_get_uri (
          struct nbd_handle *h


This makes a best effort attempt to construct an NBD URI which could be used to connect back to the same server (using nbd_connect_uri(3)).

In some cases there is not enough information in the handle to successfully create a URI (eg. if you connected with nbd_connect_socket(3)). In such cases the call returns NULL and further diagnostic information is available via nbd_get_errno(3) and nbd_get_error(3) as usual.

Even if a URI is returned it is not guaranteed to work, and it may not be optimal.

nbdinfo(1) --uri option is a way to access this API from shell scripts.


This call returns a string. The caller must free the returned string to avoid a memory leak.


On error NULL is returned.

Refer to "ERROR HANDLING" in libnbd(3) for how to get further details of the error.

The following parameters must not be NULL: h. For more information see "Non-NULL parameters" in libnbd(3).


nbd_get_uri can be called when the handle is in the following states:

 │ Handle created, before connecting   │ ❌ error                │
 │ Connecting                          │ ✅ allowed              │
 │ Connecting & handshaking (opt_mode) │ ✅ allowed              │
 │ Connected to the server             │ ✅ allowed              │
 │ Connection shut down                │ ✅ allowed              │
 │ Handle dead                         │ ✅ allowed              │


This function first appeared in libnbd 1.8.

If you need to test if this function is available at compile time check if the following macro is defined:



nbd_aio_connect_uri(3), nbd_connect_socket(3), nbd_connect_uri(3), nbd_create(3), nbd_get_errno(3), nbd_get_error(3), nbd_supports_uri(3), libnbd(3), nbdinfo(1).


Eric Blake

Richard W.M. Jones


Copyright Red Hat


This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA