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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | NOTES | COLOPHON |
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LIBTRACEEVENT(3) libtraceevent Manual LIBTRACEEVENT(3)
tep_register_comm, tep_override_comm, tep_is_pid_registered,
tep_data_comm_from_pid, tep_data_pid_from_comm, tep_cmdline_pid -
Manage pid to process name mappings.
#include <event-parse.h>
int tep_register_comm(struct tep_handle *tep, const char *comm, int pid);
int tep_override_comm(struct tep_handle *tep, const char *comm, int pid);
bool tep_is_pid_registered(struct tep_handle *tep, int pid);
const char *tep_data_comm_from_pid(struct tep_handle *pevent, int pid);
struct cmdline *tep_data_pid_from_comm(struct tep_handle *pevent, const char *comm, struct cmdline *next);
int tep_cmdline_pid(struct tep_handle *pevent, struct cmdline *cmdline);
These functions can be used to handle the mapping between pid and
process name. The library builds a cache of these mappings, which
is used to display the name of the process, instead of its pid.
This information can be retrieved from tracefs/saved_cmdlines
file.
The tep_register_comm() function registers a pid / process name
mapping. If a command with the same pid is already registered, an
error is returned. The pid argument is the process ID, the comm
argument is the process name, tep is the event context. The comm
is duplicated internally.
The tep_override_comm() function registers a pid / process name
mapping. If a process with the same pid is already registered, the
process name string is udapted with the new one. The pid argument
is the process ID, the comm argument is the process name, tep is
the event context. The comm is duplicated internally.
The tep_is_pid_registered() function checks if a pid has a process
name mapping registered. The pid argument is the process ID, tep
is the event context.
The tep_data_comm_from_pid() function returns the process name for
a given pid. The pid argument is the process ID, tep is the event
context. The returned string should not be freed, but will be
freed when the tep handler is closed.
The tep_data_pid_from_comm() function returns a pid for a given
process name. The comm argument is the process name, tep is the
event context. The argument next is the cmdline structure to
search for the next pid. As there may be more than one pid for a
given process, the result of this call can be passed back into a
recurring call in the next parameter, to search for the next pid.
If next is NULL, it will return the first pid associated with the
comm. The function performs a linear search, so it may be slow.
The tep_cmdline_pid() function returns the pid associated with a
given cmdline. The tep argument is the event context.
tep_register_comm() function returns 0 on success. In case of an
error -1 is returned and errno is set to indicate the cause of the
problem: ENOMEM, if there is not enough memory to duplicate the
comm or EEXIST if a mapping for this pid is already registered.
tep_override_comm() function returns 0 on success. In case of an
error -1 is returned and errno is set to indicate the cause of the
problem: ENOMEM, if there is not enough memory to duplicate the
comm.
tep_is_pid_registered() function returns true if the pid has a
process name mapped to it, false otherwise.
tep_data_comm_from_pid() function returns the process name as
string, or the string "<...>" if there is no mapping for the given
pid.
tep_data_pid_from_comm() function returns a pointer to a struct
cmdline, that holds a pid for a given process, or NULL if none is
found. This result can be passed back into a recurring call as the
next parameter of the function.
tep_cmdline_pid() functions returns the pid for the give cmdline.
If cmdline is NULL, then -1 is returned.
The following example registers pid for command "ls", in context
of event tep and performs various searches for pid / process name
mappings:
#include <event-parse.h>
...
int ret;
int ls_pid = 1021;
struct tep_handle *tep = tep_alloc();
...
ret = tep_register_comm(tep, "ls", ls_pid);
if (ret != 0 && errno == EEXIST)
ret = tep_override_comm(tep, "ls", ls_pid);
if (ret != 0) {
/* Failed to register pid / command mapping */
}
...
if (tep_is_pid_registered(tep, ls_pid) == 0) {
/* Command mapping for ls_pid is not registered */
}
...
const char *comm = tep_data_comm_from_pid(tep, ls_pid);
if (comm) {
/* Found process name for ls_pid */
}
...
int pid;
struct cmdline *cmd = tep_data_pid_from_comm(tep, "ls", NULL);
while (cmd) {
pid = tep_cmdline_pid(tep, cmd);
/* Found pid for process "ls" */
cmd = tep_data_pid_from_comm(tep, "ls", cmd);
}
event-parse.h
Header file to include in order to have access to the library APIs.
-ltraceevent
Linker switch to add when building a program that uses the library.
libtraceevent(3), trace-cmd(1)
Steven Rostedt <[email protected][1]>, author of libtraceevent.
Tzvetomir Stoyanov <[email protected][2]>, author of this man page.
Report bugs to <[email protected][3]>
libtraceevent is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
1. [email protected]
mailto:[email protected]
2. [email protected]
mailto:[email protected]
3. [email protected]
mailto:[email protected]
This page is part of the libtraceevent (Linux kernel trace event
library) project. Information about the project can be found at
⟨https://www.trace-cmd.org/⟩. If you have a bug report for this
manual page, see ⟨https://www.trace-cmd.org/⟩. This page was
obtained from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git⟩
on 2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-05-30.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to [email protected]
libtraceevent 1.7.3 09/24/2023 LIBTRACEEVENT(3)
Pages that refer to this page: tep_parse_saved_cmdlines(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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