STRACE(1M)           INTERACTIVE UNIX System           STRACE(1M)



          NAME
               strace - print STREAMS trace messages

          SYNOPSIS
               strace [ mid sid level ] ...

          DESCRIPTION
               The strace command without arguments writes all STREAMS
               event trace messages from all drivers and modules to its
               standard output.  These messages are obtained from the
               STREAMS log driver [log(7)].  If arguments are provided they
               must be in triplets of the form mid, sid, level, where mid
               is a STREAMS module id number, sid is a sub-id number, and
               level is a tracing priority level.  Each triplet indicates
               that tracing messages are to be received from the given
               module/driver, sub-id (usually indicating minor device), and
               priority level equal to or less than the given level.  The
               token all may be used for any member to indicate no restric-
               tion for that attribute.

               The format of each trace message output is:

               <seq> <time> <ticks> <level> <flags> <mid> <sid> <text>

                    <seq>     trace sequence number

                    <time>    time of message in hh:mm:ss

                    <ticks>   time of message in machine ticks since boot

                    <level>   tracing priority level

                    <flags>   E : message is also in the error log
                              F : indicates a fatal error
                              N : mail was sent to the system administrator

                    <mid>     module id number of source

                    <sid>     sub-id number of source

                    <text>    formatted text of the trace message

               Once initiated, strace will continue to execute until ter-
               minated by the user.

          EXAMPLES
               Output all trace messages from the module or driver whose
               module id is 41:

                    strace  41 all all

               Output those trace messages from driver/module id 41 with
               sub-ids 0, 1, or 2:


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          STRACE(1M)           INTERACTIVE UNIX System           STRACE(1M)



                    strace  41 0 1  41 1 1  41 2 0

               Messages from sub-ids 0 and 1 must have a tracing level less
               than or equal to 1.  Those from sub-id 2 must have a tracing
               level of 0.

          CAVEATS
               Due to performance considerations, only one strace process
               is permitted to open the STREAMS log driver at a time.  The
               log driver has a list of the triplets specified in the com-
               mand invocation, and compares each potential trace message
               against this list to decide if it should be formatted and
               sent up to the strace process.  Hence, long lists of tri-
               plets will have a greater impact on overall STREAMS perfor-
               mance.  Running strace will have the most impact on the tim-
               ing of the modules and drivers generating the trace messages
               that are sent to the strace process.  If trace messages are
               generated faster than the strace process can handle them,
               then some of the messages will be lost.  This last case can
               be determined by examining the sequence numbers on the trace
               messages output.

          SEE ALSO
               log(7).
               STREAMS Programmer's Guide.






























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