nbd\_aio\_peek\_command\_completed(3) LIBNBD nbd\_aio\_peek\_command\_completed(3)

# [NAME](#NAME)

nbd\_aio\_peek\_command\_completed - check if any command has completed

# [SYNOPSIS](#SYNOPSIS)

```
 #include <libnbd.h>
 int64_t nbd_aio_peek_command_completed (
           struct nbd_handle *h
         );
```

# [DESCRIPTION](#DESCRIPTION)

Return the unique positive 64 bit cookie of the first non-retired but completed command, 0 if there are in-flight commands but none of them are awaiting retirement, or -1 on error including when there are no in-flight commands. Any cookie returned by this function must still be passed to [**nbd\_aio\_command\_completed**(3)](/man/os/libnbd/nbd_aio_command_completed.3) to actually retire the command and learn whether the command was successful.

# [RETURN VALUE](#RETURN_VALUE)

This call returns a 64 bit signed integer ≥ 0.

# [ERRORS](#ERRORS)

On error -1 is returned.

Refer to "ERROR HANDLING" in [**libnbd**(3)](/man/os/libnbd/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)](/man/os/libnbd/libnbd.3).

# [VERSION](#VERSION)

This function first appeared in libnbd 1.0.

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

```
 #define LIBNBD_HAVE_NBD_AIO_PEEK_COMMAND_COMPLETED 1
```

# [SEE ALSO](#SEE_ALSO)

[**nbd\_aio\_command\_completed**(3)](/man/os/libnbd/nbd_aio_command_completed.3), [**nbd\_create**(3)](/man/os/libnbd/nbd_create.3), [**libnbd**(3)](/man/os/libnbd/libnbd.3).

# [AUTHORS](#AUTHORS)

Eric Blake

Richard W.M. Jones

# [COPYRIGHT](#COPYRIGHT)

Copyright Red Hat

# [LICENSE](#LICENSE)

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

2026-10-13 libnbd-1.25.8

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Document: nbd_aio_peek_command_completed(3) from libnbd 1.25.8-r0 (Chainguard OS)