If the wallet running on one server, I think there is only one linux wallet running but with multiple addresses on the same wallet, each user use their own address althout share the same wallet, whether the different users will influence each other if they share the same wallet with different address? whether I must write some php code to seperate the different users?
It depends on the wallet you are running on your server. If you use something like Bitcoin Core, then your rpc commands must be able to separate the users' addresses because the wallet does not know that each address is separate. If you do not do this manually, then someone could end up spending another person's Bitcoin.