err(7)
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err Special File
error-logging interface
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DESCRIPTION
The error logger character special pseudo-device is the means by
which information about various system events is obtained from
the DG/UX kernel for recording in more permanent storage, such as
a disk file. The events recorded include the starting of the
error logger, changes in the system time, and disk and tape I/O
errors. Other events may also be included on an implementation
dependent basis.
Information about logable events is collected regardless of
whether the error logger device is open. However, an
implementation of the error logger may limit the number of error
records that is stored internally. If a logable event occurs and
there is no space for the error record, one or more error records
currently in the error logger or the record for the new event may
be discarded. Space occupied by an error record is freed when
the record is read using the read system call.
The open system call makes the error logger device available for
reading. The error logger may not be opened if it is currently
open; the error ENXIO is returned on such an attempt.
The close system call makes the error logger available to be
opened again.
The read system call transfers one error record from the internal
error logger databases to the caller's buffer. The file pointer
is ignored; each call to read returns at most one, or part of
one, error record. The data returned to the user consists of a
structure of type "io_err_error_record_type", followed by
additional fields depending upon the type of the error record
(see <sys/err.h> for a complete description of the error record
returned). If the total size of the error record is greater than
the size of the caller's buffer, the error record is truncated to
the size of the caller's buffer and the remaining data is lost.
If no error record is available to be read, the read pends until
a record is available (unless the file descriptor NDELAY flag is
set).
The error logger does not support the write system call. The
error ENODEV is always returned.
There are no ioctl system calls specific to the error logger.
Other "ioctl" calls that apply to ordinary disk files also apply
DG/UX 4.00 Page 1
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err(7)
to the error logger.
Select always returns READY for write operations. Select returns
READY for read operations only if there is an error record
available to be read.
FILES
/dev/error Error logger device node
/usr/include/sys/err.h Include file with structure and constant
definitions
SEE ALSO
errdemon(1m).
DG/UX 4.00 Page 2
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