STRACE(8)                       Domain/OS BSD                        STRACE(8)




NAME
     strace - print STREAMS trace messages

SYNOPSIS
     /etc/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(4)). 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 (not
                    applicable)

          <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.

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 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 messages are lost.  This last case can be determined by
     examining the sequence numbers on the trace messages output.

SEE ALSO
     log(4)
     Programming with SysV STREAMS