Shell Programming and Scripting

you guys are wonderful!! thank you very much .. it worked for me .. with while and the if condition ...

just an additional note .. -r says it cannot update compressed archive (ie .gz) So i only tared the file and at end of while loop , i gzip

Code:

while read file
do
if [[ -f backup.tar ]]
then
tar -rPf backup.tar file
else
tar -cPf backup.tar file
fi
done
gzip backup.tar
)

its ok for me just for learning .. but is there a better and more elegant way of doing it?

I think for creating tar using your above command you don't need to use if..

You can directly use it. No need to check if it is present or not.

If you want to create .gz file what about using gzip(just thought)