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
     can 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 continues 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

     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).

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 have a greater impact on overall STREAMS performance.  Running
     strace has 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, 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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