bash 3.0支持进程内的[正则表达式]
使用下面的语法：

[[  string =~  regex  ]]

样例及注意事项：正则表达式不能使用引号引起来，引起来后，bash将作为一个整体

regx_str="abcdefgfootballgame"
echo $BASH
#if [[ $regx_str =~  'foot(ball)(.*)' ]]  
if [[ $regx_str =~  foot(ball)(.*) ]]
then
    echo The regex matches!
    echo $BASH_REMATCH 
    echo ${BASH_REMATCH[1]}
    echo ${BASH_REMATCH[2]}
fi

greet="Hello,World!"
if [[ $greet =~ [1-9] ]]; then
    printf "$greet is a number\n"
else
    printf "$greet is not a number\n"
fi