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DESCRIPTION

The tracefile gives the pathname of the file to be used for tracing. The file must exist and be writable by the calling process. All trace records are always appended to the file, so the file must be truncated to zero length to discard previous trace data. If tracing points are being disabled (see KTROP_CLEAR below), tracefile may be NULL. If using fktrace() then instead of passing a filename as tracefile, a file descriptor is passed as fd and behaviour is otherwise the same.

The ops parameter specifies the requested ktrace operation. The defined operations are:

The trpoints parameter specifies the trace points of interest. The defined trace points are:

Each tracing event outputs a record composed of a generic header followed by a trace point specific structure. The generic header is:

struct ktr_header {
	int	ktr_len;		/* length of buf */
	short	ktr_type;		/* trace record type */
	short	ktr_version;		/* trace record version */
	pid_t	ktr_pid;		/* process id */
	char	ktr_comm[MAXCOMLEN+1];	/* command name */
	struct	timespec ktr_time;	/* timestamp */
	lwpid_t	ktr_lid;
};

The ktr_len field specifies the length of the data that follows this header. The ktr_type and ktr_version fields (whose ordering in the structure depends on byte order) specify the format of this data. The ktr_pid, ktr_lid, and ktr_comm fields specify the process and command generating the record. The ktr_time field gives the time (with nanosecond resolution) that the record was generated.

The generic header is followed by ktr_len bytes of a ktr_type record of version ktr_version. The type specific records are defined in the ⟨sys/ktrace.h⟩ include file.