From: "Jeff Vian" <jvian10@xxxxxxxxxxx>
On Tue, 2005-10-25 at 14:22 -0400, Dr. Michael J. Chudobiak wrote:
Rodolfo Alcazar wrote:
> On Tue, 2005-10-25 at 13:00 -0400, Dr. Michael J. Chudobiak wrote:
>> I want to do some shell trickery so that when a user enters a command
>> like:
>>
>> ls -l
>>
>> the command is forwarded to another program as an argument. That is,
>> what actually gets executed is:
>>
>> myprog "ls -l"
>
>
> [rodolfoap] /home/rodolfoap/test > function ls() { /bin/ls|grep -v
> two; }
Thanks, that is a neat trick that I wasn't aware of, but "ls -l" was
just an example of one possible input. I want to forward every command
to my own program, not just "ls" commands.
Would it always be the same program? if so then the alias would work
well, but would be tedious to create one for every command in the
system.
More to the point what is to stop the user from simply replacing the
ls -l command that uses this function with "/bin/ls -l"?
A fairly simple script that would loop forever could read all input and
then call your program with the input as the arguments. You would have
to trap the ability to break out of the script so they could not get to
an actual shell.
something like
while 1
do
readline <read the command input line>
<put the values read into VARS here>
myprog $VARS <call your program while passing the values read>
<reset VARS here>
done
That might work, until the user hits ^C. So that would have to be trapped,
as you say. And once the user figures out $VARS is magic the rest is
history. This could prove the concept and give yourself an "adventure
shell" experience. But if it's supposed to be a security tool I would
write my own very limited shell.
{^_^}
