Records selected system events.
trace [ -a [ -g ] ] [ -f | -l ] [-b | -B] [-c] [ -d ] [ -h ] [-j Event [ ,Event ] ] [-k Event [ ,Event ] ] [ -m Message ] [ -n ] [ -o Name ] [ -o- ] [ -s ] [ -L Size ] [ -T Size ]
The trace daemon configures a trace session and starts the collection of system events. The data collected by the trace function is recorded in the trace log. A report from the trace log can be generated with the trcrpt command.
When invoked with the -a flag, the trace daemon is run asynchronously (i.e. as a background task). Otherwise, it is run interactively and prompts you for subcommands.
You can use the System Management Interface Tool (SMIT) to run the trace daemon. To use SMIT, enter:
There are three modes of trace data collection:
|Alternate (the default)||All trace events are captured in the trace log file.|
|The trace events wrap within the in-memory buffers and are not captured in the trace log file until the trace data collection is stopped.|
|The collection of trace events stops when the in-memory trace buffer fills up and the contents of the buffer are captured in the trace log file.|
|Trace buffers are allocated from either the kernel heap, or are put into separate segments. By default, buffers are allocated from the kernel heap unless the buffer size requested is too large for buffers to fit in the kernel heap, in which case they are allocated in separate segments. Allocating buffers from separate segments hinders trace performance somewhat. However, buffers in separate segments will not take up paging space, just pinned memory. The type of buffer allocation can be specified with the optional -b or -B flags.|
|-a||Runs the trace daemon asynchronously (i.e. as a background task). Once trace has been started this way, you can use the trcon, trcoff, and trcstop commands to respectively start tracing, stop tracing, or exit the trace session. These commands are implemented as links to trace.|
|-b||Allocate buffers from the kernel heap. If the requested buffer space can not be obtained from the kernel heap, the command fails.|
|-B||Allocate buffers in separate segments.|
|-c||Saves the trace log file, adding .old to its name.|
|-d||Disables the automatic start of trace data collection. Delays starting of trace data collection. Normally, the collection of trace data starts automatically when you issue the trace daemon. Use the trcon command to start the collection of trace data.|
|-f||Runs trace in a single mode. Causes the collection of trace data to stop as soon as the in-memory buffer is filled up. The trace data is then written to the trace log. Use the trcon command to restart trace data collection and capture another full buffer of data. If you issue the trcoff subcommand before the buffer is full, trace data collection is stopped and the current contents of the buffer are written to the trace log.|
|-g||Starts a trace session on a generic trace channel (channels 1 through 7). This flag works only when trace is run asynchronously (-a). The return code of the command is the channel number; the channel number must subsequently be used in the generic trace subroutine calls. To stop the generic trace session, use the command trcstop -<channel_number>.|
|-h||Omits the header record from the trace log. Normally, the tracedaemon writes a header record with the date and time (from the date command) at the beginning of the trace log; the system name, version and release, the node identification, and the machine identification (from the uname -a command); and a user-defined message. At the beginning of the trace log, the information from the header record is included in the output of the trcrpt command.|
|-k Event[,Event]||Specifies the user-defined events for which you want to collect (-j)
or exclude (-k) trace data. The Event list items can be separated
by commas, or enclosed in double quotation marks and separated by commas
|-l||Runs trace in a circular mode. The trace daemon writes the trace data to the trace log when the collection of trace data is stopped. Only the last buffer of trace data is captured. When you stop trace data collection using the trcoff command, restart it using the trconcommand.|
|-L Size||Overrides the default trace log file size of 1MB with the value stated.
Specifying a file size of zero sets the trace log
file size to the default size.
|-m Message||Specifies text to be included in the message field of the trace log header record.|
|-n||Adds information to the trace log header: lock information, hardware information, and, for each loader entry, the symbol name, address, and type.|
|-o Name||Overrides the /var/adm/ras/trcfile default trace log file and writes trace data to a user-defined file.|
|-o -||Overrides the default trace log name and writes trace data to standard output. The -c flag is ignored when using this flag.|
|-s||Stops tracing when the trace log fills. The trace daemon normally wraps the trace log when it fills up and continues to collect trace data. During asynchronous operation, this flag causes the trace daemon to stop trace data collection. (During interactive operation, the quit subcommand must be used to stop trace.)|
|-T Size||Overrides the default trace buffer size of 128KB with the value stated.
You must be root to request more than 1MB of buffer space. The maximum possible size is 268435184 bytes.
When run interactively, trace recognizes the following subcommands:
|trcon||Starts the collection of trace data.|
|trcoff||Stops the collection of trace data.|
|q or quit||Stops the collection of trace data and exits trace.|
|! Command||Runs the shell command specified by the Command parameter.|
|?||Displays the summary of trace subcommands.|
The INTERRUPT signal acts as a toggle to start and stop the collection of trace data. Interruptions are set to SIG_IGN for the traced process.
trace > !anycmd > q
trace -a; anycmd; trcstop
trace -a; sleep 10; trcstop
trace -a -o /tmp/my_trace_log; anycmd; trcstop
trace -a -k "20e,20f"; cp /bin/track /tmp/junk; trcstop
In the example above, the -k option suppresses the collection of events from the lockl and unlockl functions (20e and 20f events).
|/usr/include/sys/trcmacros.h||Defines trchook and utrchook macros.|
|/var/adm/ras/trcfile||Contains the default trace log file.|
The trcnm command, the trcrpt command, the trcstop command.
The trchook subroutine, trcgen subroutine, trcstart subroutine, trcon subroutine, trcoff subroutine, trcstop subroutine.
The trcgenk kernel service.
Trace Facility Overview in AIX Version 4.3 General Programming Concepts: Writing and Debugging Programs.
Performance Analysis with the Trace Facility in AIX Versions 3.2 and 4 Performance Tuning Guide.