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from: @(#)ktrace.1 8.1 (Berkeley) 6/6/93
.Dd $Mdocdate: September 30 2023 $ .Dt KTRACE 1 .Os .Sh NAME .Nm ktrace .Nd enable kernel process tracing .Sh SYNOPSIS .Nm ktrace .Op Fl aCcdi .Op Fl f Ar trfile .Op Fl g Ar pgid .Op Fl p Ar pid .Op Fl t Ar trstr .Nm ktrace .Op Fl aBdiT .Op Fl f Ar trfile .Op Fl t Ar trstr .Ar command .Sh DESCRIPTION .Nm ktrace enables kernel trace logging for the specified processes. By default, kernel trace data is logged to the file
a ktrace.out , unless overridden by the .Fl f option. The kernel operations traced are system calls, namei translations, signal processing and I/O.
p 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:
p .Dl $ ktrace -C
p The trace file is not human-readable; use .Xr kdump 1 to decode it.
p The options are as follows: l -tag -width 9n t Fl a Append to the trace file instead of recreating it. t Fl B Set the .Ev 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 .Xr ld.so 1 relocation sequences. t Fl C Disable tracing on all user owned processes and, if executed by root, all processes in the system. t Fl c Clear the trace points associated with the trace file or any specified processes. t Fl d Descendants; perform the operation for all current children of the designated processes. t Fl f Ar trfile Log trace records to .Ar trfile instead of
a ktrace.out . t Fl g Ar pgid Enable (disable) tracing on all processes in the process group (only one .Fl g flag is permitted). t Fl i Inherit; pass the trace flags to all future children of the designated processes. t Fl p Ar pid Enable (disable) tracing on the indicated process ID (only one .Fl p flag is permitted). t Fl T Disable userland timekeeping, making time related system calls more prevalent. t Fl t Ar 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 .Cm X are enabled.
p
l -tag -width flag -offset indent -compact Keep this list in sync with kdump(1) and ltrace(1).
t Cm c trace system calls
t Cm i trace I/O
t Cm n trace namei translations
t Cm p trace violation of
.Xr pledge 2
restrictions
t Cm s trace signal processing
t Cm S trace violation of
.Xr pinsyscalls 2
t Cm t trace various structures
t Cm u trace user data coming from
.Xr utrace 2
t Cm x trace argument vector in
.Xr execve 2
t Cm X trace environment in
.Xr execve 2
t Cm + trace the default points
.El
t Ar command Execute
.Ar command
with the specified trace flags.
.El
p The .Fl p , .Fl g , and .Ar command options are mutually exclusive. .Sh FILES l -tag -width ktrace.out -compact t Pa ktrace.out default ktrace dump file .El .Sh EXAMPLES Trace all kernel operations of process ID 34: .Dl $ ktrace -p 34
p Trace all kernel operations of processes in process group 15 and pass the trace flags to all current and future children: .Dl $ ktrace -idg 15
p Disable all tracing of process 65: .Dl $ ktrace -cp 65
p Disable tracing signals on process 70 and all current children: .Dl $ ktrace -t s -cdp 70
p Enable tracing of I/O on process 67: .Dl $ ktrace -ti -p 67
p Run the command .Xr w 1 , tracing only system calls: .Dl $ ktrace -tc w
p Disable all tracing to the file "tracedata": .Dl $ ktrace -c -f tracedata
p Disable tracing of all processes owned by the user: .Dl $ ktrace -C .Sh SEE ALSO .Xr kdump 1 , .Xr ktrace 2 , .Xr utrace 2 .Sh HISTORY The .Nm ktrace command appeared in x 4.3 Reno .