HP 3000 Manuals HP 3000 Manuals
MPE/iX System Debug Enhancements
by Patrick Murphy
Commercial Systems Division
POSIX Support
System Debug now supports HFS filename syntax in all commands and
functions that accept filenames, except those dealing with dump files.
In order to smooth the transition from MPE to POSIX filename syntax, the
environmental variable POSIX_FNAMES has been introduced. When
POSIX_FNAMES is FALSE (default), HFS syntax is recognized only for
filenames that begin with a "." or a "/". When POSIX_FNAMES is TRUE, all
filenames must be expressed in HFS form.
Another boolean environmental variable, POSIX_OS, can be read to
determine if the current system contains POSIX enhancements. For DAT,
this variable refers to the system executing the DAT program, not the
system that was dumped.
Symbolic Formatting Tag Lists
System Debug's symbolic data formatting facility uses a path
specification to identify a data structure to be displayed. An optional
list of variant tags may be included at the end of the path specification
to specify tags for tagless variants or to override stored tags.
Previous implementations of this facility contained errors, which caused
only one tag to be recognized or tagless variants only. Stored tags
could not be overridden at all. The current release corrects these
problems. In addition, tags may now be omitted from the middle of a
list, as in TAG1,,TAG3. Either the first variant or the variant
associated with the stored tag is selected when a tag is missing.
Control Characters in FV Strings
Output from the FV command has been changed to make control characters,
as well as other nonprintable characters, visible. This was done to
prevent terminal displays from being corrupted by strings containing
unexpected escape sequences.
The way nonprinting characters are displayed is similar to the way the
strings of these characters are written in Pascal source. Control
characters are displayed as #c, where c is the keyboard symbol used to
generate the character when the control key is pressed. All other
nonprinting characters are displayed as bddd, where b is the symbol for
the current output base, and the d's are up to three digits in that base.
These are all concatenated together with quoted strings to represent the
actual stored string. For example, the following shows a three-character
string with a bell character in the middle:
"a"#G"b"
This can lead to somewhat noiser output from FV than was experienced in
the past for uninitialized or null-filled strings. However, this may
have the desirable effect of calling attention to uninitialized data.
Dump Time Stamps
System memory dumps produced with this release contain time stamp
information which can be displayed by DAT. The DUMPINFO DIR command now
displays diagnostic information about elapsed dump time.
Error Management
System Debug maintains an error history stack which collects errors that
occur as commands are executed. It is not unusual for a single error
event to cause several error messages to be pushed onto the stack, while
only the last one summarizing the event is displayed on the user
terminal. The ERRLIST command may then be used to display the contents
of the error stack, including all errors pushed silently.
A new environmental variable, LOUD_ERRORS, has been introduced to deal
with situations where it is desirable to see all errors displayed as they
occur. When this variable is TRUE, all errors are displayed as they are
pushed onto the error stack. This variable is particularly useful when
more errors are generated than can be saved on the error stack. The
default for LOUD_ERRORS is FALSE.