KTRACE(1) BSD Reference Manual KTRACE(1)
ktrace - enable kernel process tracing
ktrace [-aCcdi] [-f trfile] [-g pgid] [-p pid] [-t trstr] ktrace [-adi] [-f trfile] [-t trstr] command
ktrace enables kernel trace logging for the specified processes. By de- fault, kernel trace data is logged to the file ktrace.out, unless over- ridden by the -f option. The kernel operations that are traced include system calls, namei translations, signal processing, and I/O. Once tracing is enabled on a process, trace data will be logged until ei- ther the process exits or the trace point is cleared. A traced process can generate enormous amounts of log data quickly; it is strongly sug- gested 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. -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 specified file or processes. -d Descendants; perform the operation for all current children of the designated processes. -f file Log trace records to file 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 trstr The string argument represents the kernel trace points, one per letter. The default flags are c, e, i, n, and s. The following table equates the letters with the tracepoints: c trace system calls e trace emulation changes i trace I/O n trace namei translations s trace signal processing w trace context switch points command Execute command with the specified trace flags. The -p, -g, and command options are mutually exclusive.
ktrace.out default ktrace dump file
# 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", 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
The ktrace command appeared in 4.4BSD. MirOS BSD #10-current June 6, 1993 1
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