How to Copy Files Without Prompts on Enterprise Linux 6

As I can remember, command cp never asks you the copy operation for sure except that you add -i option to enter the interactive mode. But with newer Enterprise Linux (i.e. CentOS 6.5), it will ask you all the time.
[root@test ~]# cp file1 file2
cp: overwrite `file2'? y
Let's see which cp it's using now.
[root@test ~]# which cp
alias cp='cp -i'
        /bin/cp
Oh, now we know cp is not the cp we used to be, it's an alias command. In such situation, you have several options to skip the prompts:

1. Redirect "y" to the command in advance. But I don't think it's a good practice.
[root@test ~]# echo "y" | cp file1 file2
cp: overwrite `file2'? [root@test ~]#

2. Unalias the command. It could be used to meet dynamic requirements, e.g. shell scripts.
[root@test ~]# unalias cp
[root@test ~]# which cp
/bin/cp

3. Remove or comment out the alias in the first place ~/.bashrc.
[root@test ~]# vi ~/.bashrc
...
#alias cp='cp -i'

4. Choose another alias name for 'cp -i' to distinguish them.
[root@test ~]# vi ~/.bashrc
...
alias cpi='cp -i'