strace - Writes STREAMS event trace messages to standard output
/usr/sbin/strace [mod_ID sub_ID pri_level]
Specifies the STREAMS module identification number.
Specifies a subidentification number (often corresponding to a minor
Specifies a tracing priority level. The strace command will get mes-
sages of a level equal to or less than the value in the pri_level argu-
ment. The value of the argument must be a nonnegative integer.
The strace command gets STREAMS event trace messages from STREAMS drivers
and modules via the STREAMS log driver (strlog), and writes these messages
to standard output. You can limit the messages strace receives by specify-
ing arguments to the command. All three operands must be specified
You can specify all as the value for any of the arguments in the strace
command line. The value all indicates that there are no restrictions for
You can also specify multiple sets of the command's three arguments to
obtain the messages from more than one driver or module.
More than one strace process can open the STREAMS log driver at a time.
When you invoke strace, the log driver compares the sets of arguments from
the command line with actual trace messages, returning the messages that
satisfy the criteria.
STREAMS event trace messages have the following format:
seqnum stdtime tickstime pri_level ntfycode mod_ID sub_ID msgtext
The event trace sequence number.
The time the message was sent, in the format hh:mm:ss.
The time the message was sent, measured in machine ticks since the last
The tracing priority level as defined by the STREAMS driver or module
that originates the messages.
Can be either of the following indicators:
E Indicates that the message has also been saved in the error log.
F Indicates that the message signaled a fatal error.
The module identification number of the trace message source.
The subidentification number of the trace message source.
The trace message text.
The strace command runs until terminated by the user.
Running strace with several sets of arguments can negatively affect STREAMS
performance, particularly for those modules and drivers sending the mes-
Also be aware that strace may not be able to handle a large number of mes-
sages. If drivers and modules return messages to strace too quickly, some
may be lost.
1. To display all trace messages received from the driver or module iden-
tified by mod_ID 28, enter:
% strace 28 all all
2. To display those trace messages from the driver or module identified
by mod_ID 28 and its minor devices identified by the sub_IDs 2, 3, and
% strace 28 2 all 28 3 all 28 4 all
This command line causes messages of any tracing priority level to be
3. To display the trace messages from the same driver or module and
sub_IDs, but limited to certain priority levels, enter:
% strace 28 2 0 28 3 0 28 4 1
This command line specifies that messages from driver or module 28 and
sub_IDs 2 and 3 must have a tracing priority of 0, and those from
sub_ID 4 must have a tracing priority equal to or less than 1.
Commands: strclean(8), strerr(8)