Shell Programming and Scripting

Hi

i am in learning phase of unix.
i was going through exec in a unix book. below is the command

Code:

exec n>file
exec n>>file

however when i used the exec command like below , where ex is the file name

Code:

exec 2>>ex

and then do

Code:

 ls -lrt

then again when i do the

Code:

ls -lrt

to see the size of the file ex but what i see is it again appending the o/p of the

Code:

 ls -lrt

to the file ex.

from this what i understand is after running the exec command the control is not coming out the exec command.

below is the sequence which happened to me .

Code:

 $ exec 1>>ex
$ ls -lrt
$ ls -lrt
$ ls -lrt

it is not printing the o/p on the screen when i run the ls -lrt command second time.

i am just puzzled.

regards,
scriptor