shell腳本以 .sh為后綴，里面存放著一行行要運行的linux指令。

shell腳本第一行一定為 #!/bin/bash，表示使用bash。

shell文件舉例如下：

#!/bin/bash

echo "hello shell!"

shell文件默認沒有可執行權限，因此 chmod 777 myshell.sh

./myshell.sh

交互式shell

#!/bin/bash

echo "Please input your name: "

read name

echo "I?have read your name" $name

read -p "Please input your name and height: " age height

echo "Your age?is $age, your height is $height"

上述代碼中，read用于讀取變量，-p 用于輸出提示信息

shell支持整型變量的運算

#!/bin/bash

echo "Please input two int nums: "

read -p "First num: "?a

read -p "Second num: " b

total=$(($a + $b))

echo "$a + $b = $total"

運算表達式要用雙重括號

total后的"="兩邊不能有空格

test命令的使用

1. 判斷文件是否存在

#!/bin/bash

echo "Please input filename: "

read -p "File name: " filename

test -e $filename && echo "$filename?exist!" || echo "$filename does not?exist!"???

2. 判斷字符串是否相等

#!/bin/bash

echo "Please input two strings: "

read -p "First string: " firststr

read -p "Second string: " second

test $firststr == $secondstr && echo "Equal" || echo "Not equal"

[ ] 判斷符作用類似于test，里面只能使用==或!=

#!/bin/bash

echo "Please input two strings: "

read -p "First string: " firststr

read -p "Second string: " second

[ "$firststr" == "$secondstr"?] && echo "Equal" || echo "Not equal"

以上紅色為空格，且變量兩端要加雙引號