1、打开/etc/bash.bashrc文件（需要root权限）

sudo gedit /etc/bash.bashrc
或
sudo vi /etc/bash.bashrc  

2、找到文件中的下列代码

# enable bash completion in interactive shells  
#if ! shopt -oq posix; then  
# if [ -f /usr/share/bash-completion/bash_completion ]; then  
#    . /usr/share/bash-completion/bash_completion  
#  elif [ -f /etc/bash_completion ]; then  
#    . /etc/bash_completion  
#  fi  
#fi 

将注释符号#去掉，即改成

#enable bash completion in interactive shells  
 if ! shopt -oq posix; then  
if [-f  /usr/share/bash-completion/bash_completion ]; then  
 . /usr/share/bash-completion/bash_completion  
elif [ -f /etc/bash_completion]; then  
. /etc/bash_completion  
 fi  
fi

3、最后 source一下 /etc/bash.bashrc即可， 即

shell代码,如果提示sudo下没有source命令，就把sudo去掉就行了。

sudo source /etc/bash.bashrc