1、在shell脚本中，经常遇到 “=~” ，表达形式如下：
[[ "string" =~ pattern ]]“=~” 用于判断string和右边的正则表达式pattern是否匹配
2、shell 脚本
[root@master ~]# cat hh.sh
#!/bin/bash
INT=-15a
if [[ "$INT" =~ ^-?[0-9]+$ ]]; then
echo "INT is an integer."
else
echo "INT is not an integer." >&2
exit 1
fi
[root@master ~]# sh hh.sh
INT is not an integer.
ps：正则表达式^表示起始，$表示结束，?表示0个或者1个
参考：
https://stackoverflow.com/questions/12454731/meaning-of-operator-in-shell-script
https://unix.stackexchange.com/questions/340440/bash-test-what-does-do