Is this a bug of linux's "ls" command?

UNIX for Beginners Q & A UNIX for Dummies Questions & Answers
1

I found an interesting thing with ls. do the following steps in your linux:
open a terminal
mkdir x
cd x
echo "aaa" > test1
ls
<you will see test1>

Don't close the terminal, open another terminal
rm -r x
mkdir x
cd x
echo "aaa" > test2
ls
<you will see test2>

Now go to the first terminal,
ls
<you will see nothing! no test2 here!>
cd ../x
ls
<you now see test2>

ls can not dynamically update its directory information! This could be dangerous for multiple users sharing a filesystem.
Is this a bug?

My system is ubuntu. 2.6.20-16-generic

2

I saw same thing on HP-Unix, ( B.11.00).When I did a listing the second time in terminal one, I got this message:


ls

. not found

After cd-ed back and forth, then I saw test2 in terminal one.


ls

test2