例子：删除用户脚本

批量添加指定数量的用户

cat /etc/passwd 查看当前所有用户

从一加到一百

#!/bin/bash 

cd /root/test 

ls *.tar.gz > ls.log(>覆盖) 

ls *.tgz >> ls.log(>>追加) 

for i in $(cat ls.log) 

    do 

        tar -zxvf $i &> /dev/null 

    done 

rm -rf ls.log

#!/bin/bash

read -t 10 -p "please input your choice yes/no: " choice

case $choice in

          "yes")

               echo "your choice is yes"

              ;;

           "no")

               echo "your choice is no"

              ;;

            *)

               echo "your choice is another"

              ;;

esac

#!/bin/bash 

read -t 30 -p "Please input a file name:" file 

if [ -z "$file" ] 

    then 

        echo "Error, please input a file name!" 

        exit 11 

elif [ ! -e "$file" ] 

    then 

        echo "Your input is not a file name!" 

        exit 22 

elif [ -f "$file" ] 

    then 

        echo "$file is a regular file!" 

elif [ -d "$file" ] 

    then 

        echo "$file is a directory !" 

else 

    echo "$file is another file!" 

fi

#!/bin/bash 

read -t 30 -p "Please input num1:" num1 

read -t 30 -p "Please input num2:" num2 

read -t 30 -p "Please input operator:" ope 

if [ -n "$num1" -a -n "$num2" -a -n "$ope" ] 

    then 

        test1=$(echo $num1 | sed 's/[0-9]//g') 

        test2=$(echo $num2 | sed 's/[0-9]//g') 

            if [ -z "$test1" -a -z "$test2" ] 

                then 

                    if [ "$ope" == '+' ] 

                        then 

                            result=$(($num1+$num2)) 

                    elif [ "$ope" == '-' ] 

                        then 

                            result=$(($num1-$num2)) 

                    elif [ "$ope" == '/' ] 

                        then 

                            result=$(($num1 / $num2)) 

                    elif [ "$ope" == '*' ] 

                        then 

                            result=$(($num1*num2)) 

                    else 

                        echo "Error: the input operator is worng, please input +-*/" 

                        exit 111 

                    fi 

                else 

                    echo "Error: Please input numbers!"  

                    exit 222 

                fi 

        echo "$num1 $ope $num2 is $result" 

    else 

        echo "Error: You input null value!" 

        exit 333 

fi

多分支if 条件语句

#!/bin/bash

test=$(ps aux | grep "httpd" | grep -v "grep")

if [ -n "$test" ]

    then

        echo "httpd is on"

    else

        echo "httpd is off"

        /etc/rc.d/init.d/httpd start

fi

 ps aux:查看系统中所有正在运行的进程，

 apache关键字

httpd grep -v grep：取反，不包含grep 

 判断apache服务是否启动    ps aux | grep httpd |grep -v grep

#!/bin/bash

read  -t 10 -p "input your etcname" etcname

if [-d "$etcname"]

   then

     echo "yes"

   else

     echo "no"

fi

#!/bin/bash

rate=$(df -h | grep "/dev/sda1" | awk '{print $5}' |  cut -d "%" -f 1)

if  [ "$rate" -ge "80" ]

    then

        echo "/dev/sda1 is full"

fi

#!/bin/bash

test=$(env | grep "USER" | cut -d "=" -f 2)

if [ "$test" == "root" ]

    then

        echo "Current user id root."

fi

多重条件判断

字符串的判断