MS-DOS input redirection does work after call of attrib command

[Guest]

Hi all,
I am trying to write a interactive DOS scrip that asks the user to answer
some question (using SET /P command). When I provide the answers in a text
file using the input (stdin) redirection, the input redirection seems to be
broken after a call of attrib command. Does any body encounter this problem?

My test case is simple.
I use the following script:
prompt >type testsilent.cmd
@echo off
set A=n
set B=n
set C=n
set D=n
set /P A="A="
echo.
set /P B="B="
echo.
attrib +R file.txt
set /P C="C="
echo.
set /P D="D="
echo.
echo A=%A%
echo B=%B%
echo C=%C%
echo D=%D%

The answer file is:
prompt >type answers.txt
y
y
y
y

Here the file.txt could be any file.
If I run this scrip using the following command:
prompt>testsilent.cmd < answers.txt
the result is :
A=
B=
C=
D=
A=y
B=y
C=n
D=n

Where we expect
A=
B=
C=
D=
A=y
B=y
C=y
D=y

If I comment the attrib call, the result is the one we expected.

Does any body know about this issue, if it is a known problem and if there
is any fix?
Thanks
Adnene BEN ABDALLAH

 

[Jon]

Looks like the problem is that the attrib command can also accept such
inputs (although how it uses them, if at all, is a mystery)

Change the "attrib +R file.txt" line to something like
attrib +R file.txt <file2.txt (where file2.txt is blank)
and it should work ok


Jon

 

[Pegasus \(MVP\)]

How should your batch file know how to apply
the piped input data? You expect that it knows by
sheer magic that the input is meant for the set /p
commands. This is not the case: attrib.exe will
swallow some or all of your input too! Replace
attrib.exe with some other command and you will
get a similar effect.

You must have your set /p commands in one
contiguous block if you want them to work as
expected.

 

[Guest]

Thank you for your answer.
I have an additional question. Do you know if there is in windows an
equivalent of /dev/null in UNIX, so I can redirect internal calls input to it?

Thanks
Adnene

 

[Jon]

You can use nul

eg

echo Won't see me > nul

Jon

 

[Jon]

...or more relevantly...

attrib +R file.txt <nul

Jon