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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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POSIX_TRACE_CREATE(3P) POSIX Programmer's Manual POSIX_TRACE_CREATE(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
posix_trace_create, posix_trace_create_withlog, posix_trace_flush,
posix_trace_shutdown — trace stream initialization, flush, and
shutdown from a process (TRACING)
#include <sys/types.h>
#include <trace.h>
int posix_trace_create(pid_t pid,
const trace_attr_t *restrict attr,
trace_id_t *restrict trid);
int posix_trace_create_withlog(pid_t pid,
const trace_attr_t *restrict attr, int file_desc,
trace_id_t *restrict trid);
int posix_trace_flush(trace_id_t trid);
int posix_trace_shutdown(trace_id_t trid);
The posix_trace_create() function shall create an active trace
stream. It allocates all the resources needed by the trace stream
being created for tracing the process specified by pid in
accordance with the attr argument. The attr argument represents
the initial attributes of the trace stream and shall have been
initialized by the function posix_trace_attr_init() prior to the
posix_trace_create() call. If the argument attr is NULL, the
default attributes shall be used. The attr attributes object shall
be manipulated through a set of functions described in the
posix_trace_attr family of functions. If the attributes of the
object pointed to by attr are modified later, the attributes of
the trace stream shall not be affected. The creation-time
attribute of the newly created trace stream shall be set to the
value of the system clock, if the Timers option is not supported,
or to the value of the CLOCK_REALTIME clock, if the Timers option
is supported.
The pid argument represents the target process to be traced. If
the process executing this function does not have appropriate
privileges to trace the process identified by pid, an error shall
be returned. If the pid argument is zero, the calling process
shall be traced.
The posix_trace_create() function shall store the trace stream
identifier of the new trace stream in the object pointed to by the
trid argument. This trace stream identifier shall be used in
subsequent calls to control tracing. The trid argument may only be
used by the following functions:
posix_trace_clear() posix_trace_getnext_event()
posix_trace_eventid_equal() posix_trace_shutdown()
posix_trace_eventid_get_name() posix_trace_start()
posix_trace_eventtypelist_getnext_id() posix_trace_stop()
posix_trace_eventtypelist_rewind() posix_trace_timedgetnext_event()
posix_trace_get_attr() posix_trace_trid_eventid_open()
posix_trace_get_status() posix_trace_trygetnext_event()
If the Trace Event Filter option is supported, the following
additional functions may use the trid argument:
posix_trace_get_filter() posix_trace_set_filter()
In particular, notice that the operations normally used by a trace
analyzer process, such as posix_trace_rewind() or
posix_trace_close(), cannot be invoked using the trace stream
identifier returned by the posix_trace_create() function.
A trace stream shall be created in a suspended state. If the
Trace Event Filter option is supported, its trace event type
filter shall be empty.
The posix_trace_create() function may be called multiple times
from the same or different processes, with the system-wide limit
indicated by the runtime invariant value {TRACE_SYS_MAX}, which
has the minimum value {_POSIX_TRACE_SYS_MAX}.
The trace stream identifier returned by the posix_trace_create()
function in the argument pointed to by trid is valid only in the
process that made the function call. If it is used from another
process, that is a child process, in functions defined in
POSIX.1‐2008, these functions shall return with the error
[EINVAL].
The posix_trace_create_withlog() function shall be equivalent to
posix_trace_create(), except that it associates a trace log with
this stream. The file_desc argument shall be the file descriptor
designating the trace log destination. The function shall fail if
this file descriptor refers to a file with a file type that is not
compatible with the log policy associated with the trace log. The
list of the appropriate file types that are compatible with each
log policy is implementation-defined.
The posix_trace_create_withlog() function shall return in the
parameter pointed to by trid the trace stream identifier, which
uniquely identifies the newly created trace stream, and shall be
used in subsequent calls to control tracing. The trid argument may
only be used by the following functions:
posix_trace_clear() posix_trace_get_status()
posix_trace_eventid_equal() posix_trace_getnext_event()
posix_trace_eventid_get_name() posix_trace_shutdown()
posix_trace_eventtypelist_getnext_id() posix_trace_start()
posix_trace_eventtypelist_rewind() posix_trace_stop()
posix_trace_flush() posix_trace_timedgetnext_event()
posix_trace_get_attr() posix_trace_trid_eventid_open()
If the Trace Event Filter option is supported, the following
additional functions may use the trid argument:
posix_trace_get_filter() posix_trace_set_filter()
In particular, notice that the operations normally used by a trace
analyzer process, such as posix_trace_rewind() or
posix_trace_close(), cannot be invoked using the trace stream
identifier returned by the posix_trace_create_withlog() function.
The posix_trace_flush() function shall initiate a flush operation
which copies the contents of the trace stream identified by the
argument trid into the trace log associated with the trace stream
at the creation time. If no trace log has been associated with the
trace stream pointed to by trid, this function shall return an
error. The termination of the flush operation can be polled by the
posix_trace_get_status() function. During the flush operation, it
shall be possible to trace new trace events up to the point when
the trace stream becomes full. After flushing is completed, the
space used by the flushed trace events shall be available for
tracing new trace events.
If flushing the trace stream causes the resulting trace log to
become full, the trace log full policy shall be applied. If the
trace log-full-policy attribute is set, the following occurs:
POSIX_TRACE_UNTIL_FULL
The trace events that have not yet been flushed shall be
discarded.
POSIX_TRACE_LOOP
The trace events that have not yet been flushed shall be
written to the beginning of the trace log, overwriting
previous trace events stored there.
POSIX_TRACE_APPEND
The trace events that have not yet been flushed shall be
appended to the trace log.
The posix_trace_shutdown() function shall stop the tracing of
trace events in the trace stream identified by trid, as if
posix_trace_stop() had been invoked. The posix_trace_shutdown()
function shall free all the resources associated with the trace
stream.
The posix_trace_shutdown() function shall not return until all the
resources associated with the trace stream have been freed. When
the posix_trace_shutdown() function returns, the trid argument
becomes an invalid trace stream identifier. A call to this
function shall unconditionally deallocate the resources regardless
of whether all trace events have been retrieved by the analyzer
process. Any thread blocked on one of the trace_getnext_event()
functions (which specified this trid) before this call is
unblocked with the error [EINVAL].
If the process exits, invokes a member of the exec family of
functions, or is terminated, the trace streams that the process
had created and that have not yet been shut down, shall be
automatically shut down as if an explicit call were made to the
posix_trace_shutdown() function.
For an active trace stream with log, when the
posix_trace_shutdown() function is called, all trace events that
have not yet been flushed to the trace log shall be flushed, as in
the posix_trace_flush() function, and the trace log shall be
closed.
When a trace log is closed, all the information that may be
retrieved later from the trace log through the trace interface
shall have been written to the trace log. This information
includes the trace attributes, the list of trace event types (with
the mapping between trace event names and trace event type
identifiers), and the trace status.
In addition, unspecified information shall be written to the trace
log to allow detection of a valid trace log during the
posix_trace_open() operation.
The posix_trace_shutdown() function shall not return until all
trace events have been flushed.
Upon successful completion, these functions shall return a value
of zero. Otherwise, they shall return the corresponding error
number.
The posix_trace_create() and posix_trace_create_withlog()
functions store the trace stream identifier value in the object
pointed to by trid, if successful.
The posix_trace_create() and posix_trace_create_withlog()
functions shall fail if:
EAGAIN No more trace streams can be started now. {TRACE_SYS_MAX}
has been exceeded.
EINTR The operation was interrupted by a signal. No trace stream
was created.
EINVAL One or more of the trace parameters specified by the attr
parameter is invalid.
ENOMEM The implementation does not currently have sufficient
memory to create the trace stream with the specified
parameters.
EPERM The caller does not have appropriate privileges to trace
the process specified by pid.
ESRCH The pid argument does not refer to an existing process.
The posix_trace_create_withlog() function shall fail if:
EBADF The file_desc argument is not a valid file descriptor open
for writing.
EINVAL The file_desc argument refers to a file with a file type
that does not support the log policy associated with the
trace log.
ENOSPC No space left on device. The device corresponding to the
argument file_desc does not contain the space required to
create this trace log.
The posix_trace_flush() and posix_trace_shutdown() functions shall
fail if:
EINVAL The value of the trid argument does not correspond to an
active trace stream with log.
EFBIG The trace log file has attempted to exceed an
implementation-defined maximum file size.
ENOSPC No space left on device.
The following sections are informative.
None.
None.
None.
The posix_trace_create(), posix_trace_create_withlog(),
posix_trace_flush(), and posix_trace_shutdown() functions may be
removed in a future version.
clock_getres(3p), exec(1p), posix_trace_attr_destroy(3p),
posix_trace_clear(3p), posix_trace_close(3p),
posix_trace_eventid_equal(3p),
posix_trace_eventtypelist_getnext_id(3p),
posix_trace_get_attr(3p), posix_trace_get_filter(3p),
posix_trace_getnext_event(3p), posix_trace_start(3p),
posix_trace_start(3p), time(3p)
The Base Definitions volume of POSIX.1‐2017, sys_types.h(0p),
trace.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 POSIX_TRACE_CREATE(3P)
Pages that refer to this page: trace.h(0p), exec(3p), _Exit(3p), posix_trace_attr_destroy(3p), posix_trace_attr_getclockres(3p), posix_trace_attr_getinherited(3p), posix_trace_attr_getlogsize(3p), posix_trace_clear(3p), posix_trace_flush(3p), posix_trace_get_attr(3p), posix_trace_getnext_event(3p), posix_trace_shutdown(3p), posix_trace_start(3p)
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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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