STRACE(8) Maintenance Procedures STRACE(8)


strace - print STREAMS trace messages


strace [mid sid level]...


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 (see log(4D)). 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>

trace sequence number

time of message in hh:mm:ss

time of message in machine ticks since boot

tracing priority level

E : message is also in the error log F : indicates a fatal
error N : mail was sent to the system administrator (hardcoded
as root)

module ID number of source

sub-ID number of source

formatted text of the trace message

Once initiated, strace will continue to execute until terminated by the


Example 1: A sample output of the strace command:

The following example outputs all trace messages from the module or
driver whose module ID is 41:

strace 41 all all

The following example outputs those trace messages from driver or 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.


log(4D), attributes(7)


o There is no restriction to the number of strace processes
opening the STREAMS log driver at a time.

o The log-driver records the 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, some of the messages will be lost. This last
case can be determined by examining the sequence numbers on
the trace messages output.

October 4, 1994 STRACE(8)