---
name: "tracelog"
section: "3"
platform: "linux"
package: "lttng-ust"
version: "2.16.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/tracelog"
---

# tracelog(3)

LTTng-UST printf(3)-like interface with a log level

## NAME

tracelog - LTTng-UST [printf(3)](/printf/3.md)-like interface with a log level

## SYNOPSIS

```
#include <lttng/tracelog.h>
```

```
#define tracelog(level, fmt, ...)
```

Link with **-llttng-ust -llttng-ust-common**.

## DESCRIPTION

The **tracelog()** macro is part of version 0 of the LTTng-UST API (see the “Compatibility with previous APIs” section of [**lttng-ust**(3)](/lttng-ust/3.md)).

Prefer using [**lttng\_ust\_tracelog**(3)](/lttng_ust_tracelog/3.md) which is part of version 1 of the API and has the **lttng\_ust\_** namespace.

## BUGS

If you encounter any issue or usability problem, please report it on the LTTng bug tracker \<https://bugs.lttng.org/projects/lttng-ust\>.

## RESOURCES

• LTTng project website \<http://lttng.org\>

• LTTng documentation \<http://lttng.org/docs\>

• Git repositories \<http://git.lttng.org\>

• GitHub organization \<http://github.com/lttng\>

• Continuous integration \<http://ci.lttng.org/\>

• Mailing list \<http://lists.lttng.org\> for support and development: **lttng-dev@lists.lttng.org**

• IRC channel \<irc://irc.oftc.net/lttng\>: **#lttng** on **irc.oftc.net**

## COPYRIGHTS

This macro is part of the LTTng-UST project.

This macro is distributed under the GNU Lesser General Public License, version 2.1 \<http://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html\>. See the **COPYING** \<https://github.com/lttng/lttng-ust/blob/v2.16/COPYING\> file for more details.

## THANKS

Thanks to Ericsson for funding this work, providing real-life use cases, and testing.

Special thanks to Michel Dagenais and the DORSAL laboratory \<http://www.dorsal.polymtl.ca/\> at École Polytechnique de Montréal for the LTTng journey.

## AUTHORS

LTTng-UST was originally written by Mathieu Desnoyers, with additional contributions from various other people. It is currently maintained by Mathieu Desnoyers \<mailto:mathieu.desnoyers@efficios.com\>.

## SEE ALSO

[**lttng\_ust\_tracelog**(3)](/lttng_ust_tracelog/3.md), [**lttng\_ust\_vtracelog**(3)](/lttng_ust_vtracelog/3.md)