When ssh to mac, bash version is 3

[ikuwow]

$ ssh macmini
WARNING: Your bash version is 3!
Please use bash 4.0 ~ by these commands: (Mac)
sudo bash -c 'echo /usr/local/bin/bash >> /etc/shells'
chsh -s /usr/local/bin/bash
WARNING: Your bash version is 3!
Please use bash 4.0 ~ by these commands: (Mac)
sudo bash -c 'echo /usr/local/bin/bash >> /etc/shells'
chsh -s /usr/local/bin/bash
WARNING: Your bash version is 3!
Please use bash 4.0 ~ by these commands: (Mac)
sudo bash -c 'echo /usr/local/bin/bash >> /etc/shells'
chsh -s /usr/local/bin/bash
$ echo $BASH_VERSINFO
3