shell指令碼的編寫

1、善用判斷條件  例

test -e /jason && echo "exist" || echo "not exist"

2、另一個判斷符號[]

中括號內的每個元件應用空格隔開，中括號內的常量用雙引號或者單引號設定，例子

格式：   [ "&HOME" == "$MAIL" ] 

例2： read -p "please input (Y/N): " yn

[ "$yn" == "Y" -o "$yn" == "y" ] && echo "ok,continue" && exit 0

[ "$yn" == "N" -o "$yn" == "n" ] && echo "oh,interrupt" && exit 0

echo "sorry,I dont know what is your choise" && exit 0

3、shell指令碼的預設變數

格式如下：

/path/to/srcriptsname opt1 opt2 opt3 ........

 $0                                $1     $2     $3

例子：

#!bin/bash
echo "the script name is $0"
[ -n "$1" ] && echo "the 1st parameter is $1" || exit 0
[ -n "$2" ] && echo "the 1st parameter is $2" || exit 0
[ -n "$3" ] && echo "the 1st parameter is $3" || exit 0

結果：

[email protected]:~/scripts$ sh sh04.sh afa beta thta
the script name is sh04.sh
the 1st parameter is afa
the 1st parameter is beta
the 1st parameter is thta