---
name: "libtracecmd"
section: "3"
platform: "linux"
package: "trace-cmd"
version: "3.4-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libtracecmd"
---

# libtracecmd(3)

trace-cmd library APIs

## NAME

libtracecmd - trace-cmd library APIs

## SYNOPSIS

```
#include <trace-cmd.h>
Open and close trace file:
        struct tracecmd_input *tracecmd_open(const char *file, int flags);
        struct tracecmd_input *tracecmd_open_fd(int fd, int flags);
        struct tracecmd_input *tracecmd_open_head(const char *file, int flags);
        void tracecmd_close(struct tracecmd_input *handle);
        void tracecmd_set_private(struct tracecmd_input *handle, void *data);
        void *tracecmd_get_private(struct tracecmd_input *handle);
Read tracing records from a trace file:
        int tracecmd_init_data(struct tracecmd_input *handle);
        struct tep_record *tracecmd_read_cpu_first(struct tracecmd_input *handle, int cpu);
        struct tep_record *tracecmd_read_data(struct tracecmd_input *handle, int cpu);
        struct tep_record *tracecmd_read_at(struct tracecmd_input *handle, unsigned long long offset, int *cpu);
        void tracecmd_free_record(struct tep_record *record);
        struct tep_handle *tracecmd_get_tep(struct tracecmd_input *handle);
Iterating over events in a trace file:
        int tracecmd_iterate_events(struct tracecmd_input *handle,
                                    cpu_set_t *cpus, int cpu_size,
                                    int (*callback)(struct tracecmd_input *,
                                                    struct tep_record *,
                                                    int, void *),
                                    void *callback_data);
        int tracecmd_iterate_events_multi(struct tracecmd_input **handles,
                                          int nr_handles,
                                          int (*callback)(struct tracecmd_input *,
                                                                   struct tep_record *,
                                                           int, void *),
                                          void *callback_data);
        int tracecmd_iterate_events_reverse(struct tracecmd_input *handle,
                                    cpu_set_t *cpus, int cpu_size,
                                    int (*callback)(struct tracecmd_input *,
                                                    struct tep_record *,
                                                    int, void *),
                                    void *callback_data, bool cont);
        int tracecmd_follow_event(struct tracecmd_input *handle,
                                  const char *system, const char *event_name,
                                  int (*callback)(struct tracecmd_input *,
                                                  struct tep_event *,
                                                  struct tep_record *,
                                                  int, void *),
                                  void *callback_data);
        int tracecmd_follow_missed_events(struct tracecmd_input *handle,
                                           int (*callback)(struct tracecmd_input *,
                                                           struct tep_event *,
                                                           struct tep_record *,
                                                           int, void *),
                                           void *callback_data);
        struct tracecmd_filter *tracecmd_filter_add(struct tracecmd_input handle,
                                                    const char *filter_str, bool neg);
        int *tracecmd_iterate_reset(struct tracecmd_input *handle);
Read tracing instances from a trace file:
        int tracecmd_buffer_instances(struct tracecmd_input *handle);
        const char *tracecmd_buffer_instance_name(struct tracecmd_input *handle, int indx);
        struct tracecmd_input *tracecmd_buffer_instance_handle(struct tracecmd_input *handle, int indx);
Handle time stamps from a trace file:
        unsigned long long tracecmd_get_first_ts(struct tracecmd_input *handle);
        void tracecmd_add_ts_offset(struct tracecmd_input *handle, long long offset);
        int tracecmd_get_tsc2nsec(struct tracecmd_input *handle, int *mult, int pass[]shift, unsigned long long *offset);
Get traceing peer information from a trace file:
        unsigned long long *tracecmd_get_traceid(struct tracecmd_input *handle);
        int tracecmd_get_guest_cpumap(struct tracecmd_input *handle, unsigned long long trace_id, const char **name, int *vcpu_count, const int **cpu_pid);
Mapping host and guest trace files:
        int tracecmd_map_vcpus(struct tracecmd_input **handles, int nr_handles);
        struct tracecmd_cpu_map *tracecmd_get_cpu_map(struct tracecmd_input *handle, int cpu);
        struct tracecmd_cpu_map *tracecmd_map_find_by_host_pid(struct tracecmd_input *handle,
                                                      int host_pid);
        int tracecmd_map_get_host_pid(struct tracecmd_cpu_map *map);
        struct tracecmd_input *tracecmd_map_get_guest(struct tracecmd_cpu_map *map);
        void tracecmd_map_set_private(struct tracecmd_cpu_map *map, void *priv);
        void *tracecmd_map_get_private(struct tracecmd_cpu_map *map);
Control library logs:
        int tracecmd_set_loglevel(enum tep_loglevel level);
```

## DESCRIPTION

The [libtracecmd(3)](/libtracecmd/3.md) library provides APIs to read, parse and write *[trace-cmd.dat(5)](/trace-cmd.dat/5.md)* files, recorded with *[trace-cmd(1)](/trace-cmd/1.md)* application and containing tracing information from ftrace, the official Linux kernel tracer.

## FILES

```
trace-cmd.h
        Header file to include in order to have access to the library APIs.
-ltracecmd
        Linker switch to add when building a program that uses the library.
```

## SEE ALSO

**[libtraceevent(3)](/libtraceevent/3.md)** **[libtracefs(3)](/libtracefs/3.md)** **[trace-cmd(1)](/trace-cmd/1.md)** **[trace-cmd.dat(5)](/trace-cmd.dat/5.md)**

## AUTHOR

```
Steven Rostedt <rostedt@goodmis.org[1]>
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
```

## REPORTING BUGS

Report bugs to \<**linux-trace-devel@vger.kernel.org**\[3\]\>

## LICENSE

libtracecmd is Free Software licensed under the GNU LGPL 2.1

## RESOURCES

**https://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git/**

## COPYING

Copyright (C) 2020 VMware, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL).

## NOTES

- 1\.

  rostedt@goodmis.org

  mailto:rostedt@goodmis.org

- 2\.

  tz.stoyanov@gmail.com

  mailto:tz.stoyanov@gmail.com

- 3\.

  linux-trace-devel@vger.kernel.org

  mailto:linux-trace-devel@vger.kernel.org