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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:
amp;$ ktrace -C
The trace file is not human readable; use kdump(1) to decode it.
The utility may be used only with a kernel that has been built with the "KTRACE" option in the kernel configuration file.
The options are:
| | |
| Append to the trace file instead of recreating it. | |
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| Disable tracing on all user-owned processes, and, if executed by root, all processes in the system. | |
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| Clear the specified trace points associated with the given file or processes. | |
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|
Descendants; perform the operation for all current children of the
designated processes.
See also the
| |
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| Log trace records to trfile instead of ktrace.out. | |
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|
Enable (disable) tracing on all processes in the process group (only one
| |
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|
Inherit; pass the trace flags to all future children of the designated
processes.
See also the
| |
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|
Enable (disable) tracing on the indicated process id (only one
| |
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Specify the list of trace points to enable or disable, one per letter.
If an explicit list is not specified, the default set of trace points is used.
The following trace points are supported:
| |
| c | trace system calls |
| f | trace page faults |
| i | trace I/O |
| n | trace namei translations |
| p | trace capability check failures |
| s | trace signal processing |
| t | trace various structures |
| u | userland traces generated by utrace(2) |
| w | context switches |
| y | trace sysctl(3) requests |
| + | trace the default set of trace points - c, i, n, p, s, t, u, y |
| command | |
| Execute command with the specified trace flags. | |
The
$ ktrace -i make
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
Disable all tracing to the file "tracedata":
$ ktrace -c -f tracedata
Disable tracing of all user-owned processes:
$ ktrace -C
| KTRACE (1) | August 26, 2019 |
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Please direct any comments about this manual page service to Ben Bullock. Privacy policy.
| “ | "I liken starting one's computing career with Unix, say as an undergraduate, to being born in East Africa. It is intolerably hot, your body is covered with lice and flies, you are malnourished and you suffer from numerous curable diseases. But, as far as young East Africans can tell, this is simply the natural condition and they live within it. By the time they find out differently, it is too late. They already think that the writing of shell scripts is a natural act." | ” |
| — Ken Pier, Xerox PARC | ||