vi bug?
Daniel R. Levy
(on a VAX running BSD4.1, on a 3B2/400 running SysVR2, on a 3B20S running
SysVR2, but not on a PDP 11/70 running the UNIX 4.0 system).
The trouble seems to be that vi will intercept certain ASCII sequences in
the input file on lines beginning with 'ex:' and will interpret them as if
they were commands.
For example, a file containing the two lines
ex::
ex:3:
will, when read into some versions of vi, produce the diagnostic
"Not that many lines in buffer."
This problem arose when using vi to edit ASCII database files structured into
newline-separated records with the fields separated by colons (a la
/etc/passwd) and where 'ex' was one possible entry in the first field of
a record.
Would someone who is in the know please tell me whether this behavior is
a bug or a "feature"? I certainly cannot find any mention of it in what
little documentation I have about vi (the SysV and BSD man pages on ex and
vi, and a document called "An Introduction to Display Editing using Vi").
Thank you in advance.
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Jim Webb
> The trouble seems to be that vi will intercept certain ASCII sequences in
> the input file on lines beginning with 'ex:' and will interpret them as if
> they were commands.
>
> a bug or a "feature"? I certainly cannot find any mention of it in what
> little documentation I have about vi (the SysV and BSD man pages on ex and
> vi, and a document called "An Introduction to Display Editing using Vi").
> Thank you in advance.
This is an semi-documented feature:
Mode lines are now supported. Put a line containing
ex: xxx :
in the first or last 5 lines of the file, where xxx is any ex
command you want executed when that file is read in. To make
other programs happy, it should probably be inside a comment. ----+
You can use vi: as well as ex:. (Note: no space allowed |
between the "ex" and ":". The spaces around xxx are considered |
part of the command, and so are optional.) |
|
eg /* ex: autoindent : */ <-+
It was added in version 3.7 (October 16, 1981). This and other goodies
are found in a file ex.news which comes with the vi src. On my machine,
it was in /usr/src/cmd/vi/vax/ex.news which is a vax running SVR2. I don't
know whether or not it is considered proprietary, otherwise I would have
posted it in its entirety.
--
Jim Webb "Out of phase--get help" ...!ihnp4!hropus!jrw
Daniel R. Levy
(intercepting ex: or vi: [or ei: or vx: -- yuck] in the first or last few
lines of a file being read in) is an old, old "feature" allowing for auto-
configuration of vi, and that, yawn, it had been hashed over many many
times before on the net. (Guess I have to get a copy of the compleat net
archives, then, so I won't appear stupid to the oldtimers. Postpone those
backups, Joe, gotta mount a few dozen magtapes to grep for something :-). )
I sure would have preferred that this behavior wasn't the default, requiring
a command line option or environment variable to turn it on, or at the least
that it could be turned off by a command line option or something in the
$HOME/.exrc file. In certain contexts, e.g. editing ASCII database files,
it stinks. I particularly liked the message from the fellow who said that his
version of the vi source code deleted this "feature" by #ifdef SUICIDE
preprocessor directives. (I have now found it, in the routine checkmodeline()
in ex_io.c. Not the #ifdef SUICIDE directive, but rather the suicidal code.)
Dan