listing for S
strlog, log - STREAMS log driver
mid Specifies the STREAMS module ID number for the driver or module
submitting the log message.
sid Specifies the sub-ID number of a minor device associated with the
STREAMS module or driver identified by mid.
Specifies a level for screening lower-level event messages from a
Contains several flags that can be set in various combinations. The
flags are as follows:
The message is for the error logger.
The message is for the tracer.
The message is for the console logger.
Provides a notification of a fatal error.
Makes a request to mail a copy of a message to the system
The following are additional flags. The strlog interface does not use
The message is a warning.
The message is a note.
fmt A printf style format string. This accepts the %x, %l, %o, %u, %d, %c,
and %s conversion specifications.
Numeric or character arguments for process-specific information. There
is no maximum number of arguments that can be specified.
The STREAMS log driver allows user-level processes, and STREAMS drivers and
modules, to perform error logging and event tracing. This is done via a
user interface and a kernel interface.
The interface that this driver presents to user-level processes is a subset
of the ioctl() system calls and STREAMS message formats. These processes
can be error loggers, trace loggers, or other user processes, that generate
error or event messages. The user interface collects log messages from the
log driver, and also generates log messages from user processes.
The driver also accepts log messages from STREAMS drivers and modules in
the kernel via its function call interface. The kernel interface enters
requests or calls from STREAMS drivers and modules into log messages.
STREAMS drivers and modules generate log messages by calls to the strlog()
function. Definitions used in these calls are contained in the log_ctl
structure in the </sys/strlog.h> header file. The SYNOPSIS section
describes the kernel interface.
User processes access the log driver with an open() call to
/dev/streams/log. Each open to the device will obtain a separate stream.
After a process opens /dev/streams/log, it indicates whether it is an error
logger or trace logger. It does this by issuing an I_STR ioctl() system
call containing the appropriate data and control information in a trace_ids
· For an error logger, the I_STR ioctl() contains an ic_cmd field of
I_ERRLOG with no data.
· For a trace logger, the I_STR ioctl() contains an ic_cmd field of
I_TRCLOG and a data buffer consisting of an array of one or more
If any of the fields of the trace_ids structure contain a value of -1,
/dev/streams/log will accept whatever value it receives in that field.
Otherwise, strlog only accepts messages only if the values of mid and sid
are the same as their counterparts in the trace_ids structure, and if the
message's level is equal to or less than the level value in the trace_ids
Once the logger process has sent the I_STR ioctl() call, the STREAMS log
driver begins to send log messages matching the restrictions to the logger
process. The logger process obtains the log messages via the getmsg(2)
system call. The control part of the messages passed in this call includes
a log_ctl structure, which indicates the mid, sid and level, time in ticks
since the boot time that the message was submitted, the corresponding time
in seconds since January 1, 1970, and a sequence number. The time in
seconds since January 1, 1970 is provided so that the date and time of the
message can be easily computed. The time in ticks since boot time is
provided so that the relative timing of log messages can be determined. In
addition to the information contained in the log_ctl structure, there is
also a priority indication.
The priority indication consists of a priority code and a facility code
(found in /sys/syslog.h). The valid values for priority codes are the
following, based on the setting(s) in flags:
If SL_CONSOLE is set in flags.
If SL_CONSOLE and SL_WARN are set in flags.
If SL_CONSOLE and SL_FATAL are set in flags.
If SL_CONSOLE and SL_ERROR are set in flags.
If SL_CONSOLE and SL_NOTE are set in flags.
If SL_CONSOLE and SL_TRACE are set in flags.
The valid values for facility codes are the following:
If the message originates from the kernel.
If the message originates from a user process. However, these processes
may sometimes set another facility code value instead.
A user process, other than an error or trace logger, can send a log message
to strlog(). The driver will accept only the flags and level fields of the
log_ctl structure in the control part of the message, and a properly
formatted data part of the message. The data part of the message is
properly formatted if it contains a null-terminated format string, followed
by any arguments packed one word each after the end of the string.
A different series of sequence numbers is provided for error and trace
logging streams. These sequence numbers are intended to help track the
delivery of the messages. A gap in a sequence of numbers indicates that the
logger process did not successfully deliver them. This can happen if the
logger process stops sending messages for one reason or another (see the
strace and strerr command reference pages for more information). The data
part of messages contains unexpanded text of the format string (null
terminated), followed by any arguments packed one word each after the end
of the string.
Tru64 UNIX does not provide a console logger. Note, however, that other
systems may provide console loggers.
If any of the following conditions occurs, strlog() driver's ioctl()
command sets errno to the corresponding value:
The I_TRCLOG ioctl() call did not contain any trace_ids structures.
The I_STR ioctl() call could not be recognized.
The driver does not return any errors for incorrectly formatted messages
that user processes send.
The following examples illustrate how to use the strlog interface for some
1. This code example segment illustrates how a STREAMS module can
generate a console log message:
"TMUX driver (minor:%d) suffers resource shortage.",
2. This code example illustrates how a user process can register itself
with the STREAMS log driver using the ioctl() command, I_ERRLOG.
struct strioctl iocerr:
iocerr.ic_cmd = I_ERRLOG;
iocerr.ic_timout = 0;
iocerr.ic_len = 0;
iocerr.ic_dp = NULL;
ioctl(logfd, I_STR, &iocerr)
Specifies the clone interface.
Specifies the header file for STREAMS logging.
Specifies the header file for STREAMS options and ioctl() commands.
Commands: strace(8), strerr(8)
Interfaces clone(7), streamio(7)
Functions: getmsg(2), putmsg(2), write(2)
listing for S