---
name: "ltrace"
section: "1"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["linux", "openbsd"]
url: "https://new.carta.tech/ltrace"
---

# ltrace(1)

shared library function call tracer

## NAME

**ltrace** – shared library function call tracer

## SYNOPSIS

**ltrace** \[**-ai**\] \[**-f** *trfile*\] \[**-t** *trstr*\] \[**-u** *trspec*\] *command*

## DESCRIPTION

**ltrace** enables shared library function calls issued by the specified processes to be traced using the [utrace(2)](/utrace/2.md) user tracing facility. By default, call trace data is logged to the file *ktrace.out*, unless overridden by the **-f** option. Each function call is traced as a pair of KTRFAC\_USER entries; the first entry contains the shared library containing the symbol being called, and the second entry contains the symbol name.

Once tracing is enabled on a process, trace data will be logged until either the process exits or the trace point is cleared with [ktrace(1)](/ktrace/1.md). A traced process can generate enormous amounts of log data quickly; it is strongly suggested that users memorize how to disable tracing before attempting to trace a process. The following command is sufficient to disable tracing on all user owned processes and, if executed by root, all processes:

```
$ ktrace -C
```

The trace file is not human-readable; use [kdump(1)](/kdump/1.md) to decode it.

The options are as follows:

- **-a**

  Append to the trace file instead of recreating it.

- **-f** *trfile*

  Log trace records to *trfile* instead of *ktrace.out*.

- **-i**

  Inherit; pass the trace flags to all future children of the designated processes.

- **-t** *trstr*

  The string argument represents the kernel trace points, one per letter. The default is just **u**. The following table equates the letters with the trace points:

  - **c**

    trace system calls

  - **i**

    trace I/O

  - **n**

    trace namei translations

  - **p**

    trace violation of pledge(2) restrictions

  - **s**

    trace signal processing

  - **t**

    trace various structures

  - **u**

    trace user data coming from [utrace(2)](/utrace/2.md)

  - **x**

    trace argument vector in [execve(2)](/execve/2.md)

  - **X**

    trace environment in [execve(2)](/execve/2.md)

  - **+**

    trace the default points

- **-u** *trspec*

  Restrict the trace to a list of shared objects and/or function names, as specified by the *trspec* argument. The trace specification is a comma-separated list of library names, followed by a colon (:), and a comma-separated list of function names. Each list can be empty. Each list member may end with a star (\*) to only match the beginning of a name. An exclamation mark at the beginning of a list turns it into a rejection list, causing all unmatched names to be traced. Library names are compared without their version number and ‘.so’ suffix.

- *command*

  Execute *command* with the specified trace flags.

## FILES

- *ktrace.out*

  Default **ltrace** dump file.

## EXAMPLES

Trace all shared library function calls from [wc(1)](/wc/1.md) reading the message of the day:

```
$ ltrace wc -lh /etc/motd
```

Trace only the shared library function calls in *libutil.so*:

```
$ ltrace -u libutil wc -lh /etc/motd
```

Trace all the shared library function calls but those in *libc.so*:

```
$ ltrace -u "!libc" wc -lh /etc/motd
```

Trace all the shared library function calls with names starting "fmt":

```
$ ltrace -u ":fmt*" wc -lh /etc/motd
```

Trace all shared library function calls, as well as all system calls:

```
$ ltrace -t cu wc -lh /etc/motd
```

## SEE ALSO

[kdump(1)](/kdump/1.md), [ktrace(1)](/ktrace/1.md), [ktrace(2)](/ktrace/2.md), [utrace(2)](/utrace/2.md)

## HISTORY

The **ltrace** command appeared in OpenBSD 5.4.