jcw@cvl.UUCP (Jay C. Weber) (08/22/83)
Here are a few items that DOS 2.0 users should be interested in,
some are bad and some are good.
1) The DOS 1.1 system calls for reading from and writing to the
console were changed in 2.0 to be reading from stdin and writing to
stdout. This is nice in that DOS 1.1 programs can have their i/o
redirected, but there are some problems. When writing to stdout
all tabs are expanded; I found this out when trying to get my
"unexpand" program to work with writing to stdout. Also, the system
calls to read are of two types; echo character read and no echo
character read. The problem is, a user program doesn't know
which to do -- if you are typing it should be echo, redirected from
a file it should be noecho. In addition, I have had some programs
that don't see EOF on redirected input, hanging and not being
CTRL-BREAKable.
2) 2.0 interprets [<>|] as file redirection characters, but if you
enclose them in double quotes (") they are sent to the program
literally (so are the quotes). Single quotes do not do the same
thing. As far as I can tell, there is no way to escape the quotes.
3) In interactive command mode, the % sign has no special function.
In batch mode, it is used for argument substitution. However, when
the following character is not a digit in batch mode this is what
it does:
echo %t ==> t
echo %%t ==> %t
echo %%%t ==> %t
echo "%t" ==> "t"
2.0 ain't UN*X but better than CP/M,
Jay Weber
{..!seismo!rlgvax!cvl!jcw} and soon to be
{..!seismo!rochester!????}