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KDUMP(1) General Commands Manual KDUMP(1)

kdumpdisplay kernel trace data

kdump [-dHlnRTXx] [-f file] [-m maxdata] [-p pid] [-t trstr] [-u label]

kdump displays the kernel trace files produced with ktrace(1) in human-readable format. By default, the file ktrace.out in the current directory is displayed, unless overridden by the -f option.

The options are as follows:

Display all numbers in decimal. By default, values are printed out in hexadecimal.
Display the specified file instead of ktrace.out. Specifying ‘-’ will read from standard input.
Display thread identifiers.
Loop reading the trace file, once the end-of-file is reached, waiting for more data.
Display at most maxdata bytes when decoding I/O.
Suppress ad hoc translations. Normally kdump tries to decode many system calls into a more human-readable format. For example, ioctl(2) values are replaced with the macro name and errno values are replaced with the strerror(3) string. Suppressing this feature yields a more consistent output format and is easily amenable to further processing.
Show output only for the pid specified.
Display relative timestamps (time since previous entry).
Display absolute timestamps for each entry (seconds since the Epoch).
If both options are specified, display timestamps relative to trace start.
Select which tracepoints to display. The argument can contain one or more of the following letters. By default all trace points except for X are enabled.

trace system calls
trace I/O
trace namei translations
trace violation of pledge(2) restrictions
trace signal processing
trace various structures
trace user data coming from utrace(2)
trace argument vector in execve(2)
trace environment in execve(2)
trace the default points
Display utrace(2) tracepoints having utrace(2) label label as strings with vis(3) escaping, without ktrace(2) header information.
Display I/O data with hexadecimal data and printable ASCII characters side by side.
Display I/O data in hexadecimal.

The -t and -u options are mutually exclusive; the last one specified overrides any previous ones.

default ktrace dump file


The kdump command appeared in 4.3BSD-Reno.

September 30, 2023 OpenBSD-7.4