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ktrace(1) [opendarwin man page]

KTRACE(1)						    BSD General Commands Manual 						 KTRACE(1)

ktrace -- enable kernel process tracing SYNOPSIS
ktrace [-aCcdi] [-f trfile] [-g pgrp | -p pid] [-t trstr] ktrace [-adi] [-f trfile] [-t trstr] command DESCRIPTION
The ktrace command enables kernel trace logging for the specified processes. Kernel trace data is logged to the file ktrace.out. 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 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: $ 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 following table equates the letters with the trace- points: c trace system calls n trace namei translations i trace I/O s trace signal processing u userland traces w context switches command Execute command with the specified trace flags. The -p, -g, and command options are mutually exclusive. EXAMPLES
# 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 SEE ALSO
kdump(1) BUGS
Only works if file is a regular file. HISTORY
The ktrace command appeared in 4.4BSD. BSD
June 6, 1993 BSD

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KTRACE(2)						      BSD System Calls Manual							 KTRACE(2)

ktrace -- process tracing LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/types.h> #include <sys/uio.h> #include <sys/ktrace.h> int ktrace(const char *tracefile, int ops, int trpoints, pid_t pid); int fktrace(int fd, int ops, int trpoints, pid_t pid); DESCRIPTION
The ktrace() function enables or disables tracing of one or more processes. Users may only trace their own processes. Only the super-user can trace setuid or setgid programs. 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: KTROP_SET Enable trace points specified in trpoints. KTROP_CLEAR Disable trace points specified in trpoints. KTROP_CLEARFILE Stop all tracing. KTRFLAG_DESCEND The tracing change should apply to the specified process and all its current children. The trpoints parameter specifies the trace points of interest. The defined trace points are: KTRFAC_SYSCALL Trace system calls. KTRFAC_SYSRET Trace return values from system calls. KTRFAC_NAMEI Trace name lookup operations. KTRFAC_GENIO Trace all I/O (note that this option can generate much output). KTRFAC_PSIG Trace posted signals. KTRFAC_CSW Trace context switch points. KTRFAC_EMUL Trace emulation changes. KTRFAC_INHERIT Inherit tracing to future children. 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 */ pid_t ktr_pid; /* process id */ char ktr_comm[MAXCOMLEN+1]; /* command name */ struct timeval ktr_time; /* timestamp */ caddr_t ktr_buf; }; The ktr_len field specifies the length of the ktr_type data that follows this header. The ktr_pid and ktr_comm fields specify the process and command generating the record. The ktr_time field gives the time (with microsecond resolution) that the record was generated. The ktr_buf is an internal kernel pointer and is not useful. The generic header is followed by ktr_len bytes of a ktr_type record. The type specific records are defined in the <sys/ktrace.h> include file. RETURN VALUES
On successful completion a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to show the error. ERRORS
ktrace() will fail if: [ENOTDIR] A component of the path prefix is not a directory. [EINVAL] The pathname contains a character with the high-order bit set. [ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters. [ENOENT] The named tracefile does not exist. [EACCES] Search permission is denied for a component of the path prefix. [ELOOP] Too many symbolic links were encountered in translating the pathname. [EIO] An I/O error occurred while reading from or writing to the file system. SEE ALSO
kdump(1), ktrace(1) HISTORY
A ktrace function call first appeared in 4.4BSD. BSD
June 4, 1993 BSD
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