strace(1M)                                                       strace(1M)


   NAME
         strace - print STREAMS trace messages

   SYNOPSIS
         strace [ mid sid level ] ...

   DESCRIPTION
         strace 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 restriction 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 terminated by
         the user.

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

               strace  41 all all





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   strace(1M)                                                       strace(1M)


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

               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.

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

   NOTES
         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 command 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 triplets will have a greater impact on overall STREAMS
         performance.  Running strace will have the most impact on the timing
         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.




























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