ktrace.tproj/ktrace.1

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  32 .\"     @(#)ktrace.1    8.1 (Berkeley) 6/6/93
  33 .\" $FreeBSD: src/usr.bin/ktrace/ktrace.1,v 1.8.2.5 2001/08/16 13:16:53 ru Exp $
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  35 .Dd June 6, 1993
  36 .Dt KTRACE 1
  37 .Os
  38 .Sh NAME
  39 .Nm ktrace
  40 .Nd enable kernel process tracing
  41 .Sh SYNOPSIS
  42 .Nm
  43 .Op Fl aCcdi
  44 .Op Fl f Ar trfile
  45 .Op Fl g Ar pgrp | Fl p Ar pid
  46 .Op Fl t Ar trstr
  47 .Nm
  48 .Op Fl adi
  49 .Op Fl f Ar trfile
  50 .Op Fl t Ar trstr
  51 .Ar command
  52 .Sh DESCRIPTION
  53 The
  54 .Nm
  55 command enables kernel trace logging for the specified processes.
  56 Kernel trace data is logged to the file
  57 .Pa ktrace.out .
  58 The kernel operations that are traced include system calls, namei
  59 translations, signal processing, and
  60 .Tn I/O .
  61 .Pp
  62 Once tracing is enabled on a process, trace data will be logged until
  63 either the process exits or the trace point is cleared.
  64 A traced process can generate enormous amounts of log data quickly;
  65 It is strongly suggested that users memorize how to disable tracing before
  66 attempting to trace a process.
  67 The following command is sufficient to disable tracing on all user owned
  68 processes, and, if executed by root, all processes:
  69 .Pp
  70 .Dl \&$ ktrace -C
  71 .Pp
  72 The trace file is not human readable; use
  73 .Xr kdump 1
  74 to decode it.
  75 .Pp
  76 The options are as follows:
  77 .Bl -tag -width indent
  78 .It Fl a
  79 Append to the trace file instead of recreating it.
  80 .It Fl C
  81 Disable tracing on all user owned processes, and, if executed by root, all
  82 processes in the system.
  83 .It Fl c
  84 Clear the trace points associated with the specified file or processes.
  85 .It Fl d
  86 Descendants; perform the operation for all current children of the
  87 designated processes.
  88 .It Fl f Ar file
  89 Log trace records to
  90 .Ar file
  91 instead of
  92 .Pa ktrace.out .
  93 .It Fl g Ar pgid
  94 Enable (disable) tracing on all processes in the process group (only one
  95 .Fl g
  96 flag is permitted).
  97 .It Fl i
  98 Inherit; pass the trace flags to all future children of the designated
  99 processes.
 100 .It Fl p Ar pid
 101 Enable (disable) tracing on the indicated process id (only one
 102 .Fl p
 103 flag is permitted).
 104 .It Fl t Ar trstr
 105 The string argument represents the kernel trace points, one per letter.
 106 The following table equates the letters with the tracepoints:
 107 .Pp
 108 .Bl -tag -width flag -compact
 109 .It Cm c
 110 trace system calls
 111 .It Cm n
 112 trace namei translations
 113 .It Cm i
 114 trace
 115 .Tn I/O
 116 .It Cm s
 117 trace signal processing
 118 .It Cm u
 119 userland traces
 120 .It Cm w
 121 context switches
 122 .El
 123 .It Ar command
 124 Execute
 125 .Ar command
 126 with the specified trace flags.
 127 .El
 128 .Pp
 129 The
 130 .Fl p ,
 131 .Fl g ,
 132 and
 133 .Ar command
 134 options are mutually exclusive.
 135 .Sh EXAMPLES
 136 # trace all kernel operations of process id 34
 137 .Dl $ ktrace -p 34
 138 .Pp
 139 # trace all kernel operations of processes in process group 15 and
 140 # pass the trace flags to all current and future children
 141 .Dl $ ktrace -idg 15
 142 .Pp
 143 # disable all tracing of process 65
 144 .Dl $ ktrace -cp 65
 145 .Pp
 146 # disable tracing signals on process 70 and all current children
 147 .Dl $ ktrace -t s -cdp 70
 148 .Pp
 149 # enable tracing of
 150 .Tn I/O
 151 on process 67
 152 .Dl $ ktrace -ti -p 67
 153 .Pp
 154 # run the command "w", tracing only system calls
 155 .Dl $ ktrace -tc w
 156 .Pp
 157 # disable all tracing to the file "tracedata"
 158 .Dl $ ktrace -c -f tracedata
 159 .Pp
 160 # disable tracing of all processes owned by the user
 161 .Dl $ ktrace -C
 162 .Sh SEE ALSO
 163 .Xr kdump 1
 164 .Sh BUGS
 165 Only works if
 166 .Ar file
 167 is a regular file.
 168 .Sh HISTORY
 169 The
 170 .Nm
 171 command appeared in
 172 .Bx 4.4 .