strace(ADM)                     19 June 1992                     strace(ADM)


 Name

    strace - print STREAMS trace messages

 Syntax

    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(M)).  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

    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(M)

 Diagnostics

    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 for-
    matted 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 out-
    put.