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KTRACE(1) FreeBSD General Commands Manual KTRACE(1) NAME ktrace - enable kernel process tracing SYNOPSIS ktrace [-aCcdi] [-f trfile] [-g pgid] [-p pid] [-t trstr] ktrace [-aBdiT] [-f trfile] [-t trstr] command DESCRIPTION ktrace enables kernel trace logging for the specified processes. By default, kernel trace data is logged to the file ktrace.out, unless overridden by the -f option. The kernel operations traced are system calls, namei translations, signal processing and I/O. Once tracing is enabled on a process, trace data will be logged until either the process exits or the trace point is cleared. 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) to decode it. The options are as follows: -a Append to the trace file instead of recreating it. -B Set the LD_BIND_NOW environment variable to specify that the dynamic linker should process relocations immediately instead of as they are encountered. This eliminates the resulting ld.so(1) relocation sequences. -C Disable tracing on all user owned processes and, if executed by root, all processes in the system. -c Clear the trace points associated with the trace file or any specified processes. -d Descendants; perform the operation for all current children of the designated processes. -f trfile Log trace records to trfile instead of ktrace.out. -g pgid Enable (disable) tracing on all processes in the process group (only one -g flag is permitted). -i Inherit; pass the trace flags to all future children of the designated processes. -p pid Enable (disable) tracing on the indicated process ID (only one -p flag is permitted). -T Disable userland timekeeping, making time related system calls more prevalent. -t trstr Select which information to put into the dump file. The argument can contain one or more of the following letters. By default all trace points except for X are enabled. c trace system calls i trace I/O n trace namei translations p trace violation of pledge(2) restrictions s trace signal processing S trace violation of pinsyscalls(2) t trace various structures u trace user data coming from utrace(2) x trace argument vector in execve(2) X trace environment in execve(2) + trace the default points command Execute command with the specified trace flags. The -p, -g, and command options are mutually exclusive. FILES ktrace.out default ktrace dump file EXAMPLES Trace all kernel operations of process ID 34: $ ktrace -p 34 Trace all kernel operations of processes in process group 15 and pass the trace flags to all current and future children: $ ktrace -idg 15 Disable all tracing of process 65: $ ktrace -cp 65 Disable tracing signals on process 70 and all current children: $ ktrace -t s -cdp 70 Enable tracing of I/O on process 67: $ ktrace -ti -p 67 Run the command w(1), tracing only system calls: $ ktrace -tc w Disable all tracing to the file "tracedata": $ ktrace -c -f tracedata Disable tracing of all processes owned by the user: $ ktrace -C SEE ALSO kdump(1), ktrace(2), utrace(2) HISTORY The ktrace command appeared in 4.3BSD-Reno. FreeBSD 14.1-RELEASE-p8 December 15, 2023 FreeBSD 14.1-RELEASE-p8