strace(8)                           CLIX                           strace(8)



  NAME

    strace - Displays 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 stdout.  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

    Where:

    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.




  2/94 - Intergraph Corporation                                              1

  strace(8)                           CLIX                           strace(8)



  EXAMPLES

    1.  To output all trace messages from the module or driver whose module ID
        is 41, enter the following:

        strace 41 all all


    2.  To output those trace messages from driver/module ID 41 with sub-IDs
        0, 1, or 2, enter the following:

        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.

  FILES

    /dev/log   STREAMS log driver

  NOTES

    Because of 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.

  DIAGNOSTICS

    Cannot open /dev/log
           Is displayed if strace is unable to access the STREAMS log driver.

    tracer already exists
           Is displayed if there is already a strace process running on the
           system.

  EXIT VALUES

    The strace command will exit with a value of 1 if it encounters a problem.

  RELATED INFORMATION

    Files: log(7)




  2                                              Intergraph Corporation - 2/94