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shell脚本判断输入变量或参数是否为空
例1，判断变量
read -p "input a word :" word
if [ ! -n "$word" ] ;then echo "you have not input a word!" else echo "the word you input is $word" fi
例2，判断输入参数
#!/bin/bash
if [ ! -n "$1" ] ;then echo "you have not input a word!" else echo "the word you input is $1" fi 以下方法未验证，大家做下测试。
例3，直接通过变量判断
#!/bin/sh
para1= if [ ! $para1 ]; then echo "IS NULL" else echo "NOT NULL" fi
例4，使用test判断
#!/bin/sh
dmin= if test -z "$dmin" then echo "dmin is not set!" else echo "dmin is set !" fi
例5，使用""判断
#!/bin/sh
dmin= if [ "$dmin" = "" ] then echo "dmin is not set!" else echo "dmin is set !" fi
完整示例，以下脚本用在系统启动时:
#!/bin/bash
(责任编辑：IT)echo "Input Param Is [$1]" if [ ! -n "$1" ] ;then echo "you have not input a null word!" ./app1;./app12;./app123 elif [ $1 -eq 2 ];then ./app12;./app123 elif [ $1 -eq 90 ];then echo "yy"; fi |