🚀 go-pugleaf

John Savage <koala@sydney.dialix.com.au> wrote:

>Amongst the myriad shortcomings of MSDOS we must include the pair:
>
>  *  FIND does not return an errorlevel to confirm a match
>  *  COPY does not copy a file of length 0

Actually, FIND does return an errorlevel in MS-DOS v6 or later:

	0	At least one match was found.
	1	No matches were found.
	2	An error occurred during the search.

If the target audience is running v6+, you can dispense with the COPY
trick altogether, as is shown below:

find "rem " /i < \autoexec.bat > nul
if not errorlevel 1 echo There were REMarked lines in your AUTOEXEC.BAT.

Note: FIND in MS-DOS v5+ includes the /I switch, which performs a
case-insensitive match on the search string.

>type %1 | find "xyz" >tmp1
>copy tmp1 tmp0 > \nul
>if exist tmp0 echo %1 contained the string xyz

Here's a suggestion for a little extra performance.  Under MS-DOS,
copying a zero-byte file actually results in the deletion of the target
file.  So ....

	find "xyz" < %1 > tmp1
	copy /b tmp1+,, > nul
	if exist tmp1 echo %1 contained the string "xyz".
	if exist tmp1 del tmp1 > nul

By copying the semaphore file onto itself, we don't have to delete it if
the test turns out negative, and we don't have to worry about deleting
it beforehand.  Of course, in a small batch like this one the savings
are negligible; however, if this were a long, complicated batch file we
could use an evar to hold the result of the first "if exist" test, and
then simply use that evar throughout in order to avoid extra disk
accesses.

Also, I used redirection instead of a pipe to FIND in order to save a
temp file--a pipe creates two temp files per instance.  Again, this is a
minor point in this example, but could add up to large savings in more
extensive batch programs.


--
Robert B. Clark <rclark@iquest.net>
"Anyone who considers protocol unimportant has never dealt with a cat."  --L. Long