shell脚本练习.txt

============================if语句：
#!/bin/bash
function check_param(){
grep -q ^$1 /etc/passwd
if [ $# -eq 0 ];then
        echo "please input param"
        return 1
elif [ $? -eq 0 ];then
        echo "$1 exist"
        return 0
else
        echo "$1 not exist"
        return 1
fi
}
check_param $1
=========================Here Documents使用：
cat <<END
        1) tom
        2) bob
        3) mary
END
==========================case语句
#!/bin/bash


function select_user(){
cat <<end
        1) tom
        2) bob

        3) jack
end
read -p "please select name: " name
}


function echo_result(){
case $name in
        1)
                echo "tom"
                ;;
        2)
                echo "bob"
                ;;
        3)
                echo "jack"
                ;;
        *)
                echo "you select error"
                return 1
                ;;
esac
}

main(){
select_user
echo_result
until [ $? -eq 0 ];
do
        select_user