error(HW)

error -- kernel error output device file

Description

Kernel error messages are collected and made available to error logging daemons through /dev/error. /dev/error is a read-only character special file which returns one error message per read with no EOF character.

When the system is booted, the bcheckrc(ADM) script starts the syslogd(ADM) daemon to filter messages from /dev/error. Two internally defined log files are written to:

Error messages are appended to the system error log file /usr/adm/messages.
Device initialization messages are written to the configuration log file /usr/adm/hwconfig.

Other log files that may be written to are defined in the file /etc/syslog.conf.

Any process can read /dev/error or arrange to be signaled when errors are queued in /dev/error. (Note that you can also use select(S) to do this.) The following ioctl causes the error device to signal the process with SIGUSR1 when an error message is queued in /dev/error.

   #include <signal.h>
   #include <sys/eio.h>
   #include <fcntl.h>
   ...
   int fd;
   ...
   fd = open("/dev/error", O_RDONLY);
   ioctl(fd, EMSG_SIG, SIGUSR1);

Before exiting, the process must return /dev/error to its normal state. Do this with the following ioctl:

   ...
   ioctl(fd,EMSG_NOSIG, 0);
   ...

Diagnostics

The following error messages may be displayed on the console. See messages(M) for general information about kernel error messages, including a list of generic device driver errors.

WARNING: err: Error log buffer overflow
WARNING: err: Error log overflow

The error message driver will overwrite the oldest messages if the log or the log buffer overflows.

Limitations

Panic error messages are not logged in /dev/error.

Files

/dev/error: character special file that allows read-only access to the error driver (err)
/etc/bcheckrc: script that starts syslogd
/usr/adm/hwconfig: device initialization log file
/usr/adm/messages: system error log file
/etc/syslog.conf: syslogd configuration file that defines other log files

Standards conformance