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NAME |SYNOPSIS |DESCRIPTION |RETURN VALUE |EXAMPLE |FILES |SEE ALSO |AUTHOR |REPORTING BUGS |LICENSE |RESOURCES |COPYING |NOTES |COLOPHON | |
LIBTRACEFS(3) libtracefs ManualLIBTRACEFS(3)tracefs_trace_is_on, tracefs_trace_on, tracefs_trace_off, tracefs_trace_on_get_fd, tracefs_trace_on_fd, tracefs_trace_off_fd - Functions to enable or disable tracing.
#include <tracefs.h> inttracefs_trace_is_on(struct tracefs_instance *instance); inttracefs_trace_on(struct tracefs_instance *instance); inttracefs_trace_off(struct tracefs_instance *instance); inttracefs_trace_on_get_fd(struct tracefs_instance *instance); inttracefs_trace_on_fd(intfd); inttracefs_trace_off_fd(intfd);
This set of functions can be used to check, enable or disable writing to the ring buffer in the given trace instance. The tracing is enabled when writing to the ring buffer is enabled. Thetracefs_trace_is_on()function checks if tracing is enabled for the giveninstance. Ifinstance is NULL, the top instance is used. Thetracefs_trace_on()andtracefs_trace_off()functions set the tracing in theinstance to enable or disable state. Ifinstance is NULL, the top instance is used. Thetracefs_trace_on_get_fd()function returns a file descriptor to the "tracing_on" file from the giveninstance. Ifinstance is NULL, the top trace instance is used. The returned descriptor can be used for fast enabling or disabling the tracing of the instance. Thetracefs_trace_on_fd()andtracefs_trace_off_fd()functions set the tracing state to enable or disable using the givenfd. This file descriptor must be opened for writing withtracefs_trace_on_get_fd(3) of the desired trace instance. These functions are faster thantracefs_trace_onandtracefs_trace_off.
Thetracefs_trace_is_on()function returns 0 if tracing is disable, 1 if it is enabled or -1 in case of an error. Thetracefs_trace_on_get_fd()function returns a file descriptor to "tracing_on" file for reading and writing, which must be closed wuth close(). In case of an error -1 is returned. Thetracefs_trace_on(),tracefs_trace_off(),tracefs_trace_on_fd() andtracefs_trace_off_fd()functions return -1 in case of an error or 0 otherwise.
#include <tracefs.h> int ret; ret = tracefs_trace_is_on(NULL); if (ret == 0) { /* Tracing is disabled in the top instance */ } else if (ret == 1) { /* Tracing is enabled in the top instance */ } else { /* Error getting tracing state of the top instance */ } ... if (!tracefs_trace_on(NULL)) { /* Enabled tracing in the top instance */ ... if (!tracefs_trace_off(NULL)) { /* Disabled tracing in the top instance */ } else { /* Error disabling tracing in the top instance */ } } else { /* Error enabling tracing in the top instance */ } ... int fd = tracefs_trace_on_get_fd(NULL); if (fd < 0) { /* Error opening tracing_on file */ } ... if (!tracefs_trace_on_fd(fd)) { /* Enabled tracing in the top instance */ ... if (!tracefs_trace_off_fd(fd)) { /* Disabled tracing in the top instance */ } else { /* Error disabling tracing in the top instance */ } } else { /* Error enabling tracing in the top instance */ } ... close(fd);tracefs.h Header file to include in order to have access to the library APIs.-ltracefs Linker switch to add when building a program that uses the library.
libtracefs(3),libtraceevent(3),trace-cmd(1)
Steven Rostedt<rostedt@goodmis.org[1]>Tzvetomir Stoyanov<tz.stoyanov@gmail.com[2]>
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
libtracefs is Free Software licensed under the GNU LGPL 2.1
https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/
Copyright (C) 2021 VMware, Inc. Free use of this software is granted under the terms of the GNU Public License (GPL).
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
This page is part of thelibtracefs (Linux kernel trace file system 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/libtracefs.git⟩ on 2025-08-11. (At that time, the date of the most recent commit that was found in the repository was 2025-06-02.) 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 isnot part of the original manual page), send a mail to man-pages@man7.orglibtracefs 1.7.0 12/22/2023LIBTRACEFS(3)Pages that refer to this page:tracefs_trace_is_on(3)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |