shell/ target=_blank class=infotextkey>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
得到的结果为: IS NULL
#!/bin/sh
para1=
if [ ! $para1 ]; then
echo "IS NULL"
else
echo "NOT NULL"
fi
例4，使用test判断
得到结果: dmin is not set!
#!/bin/sh
dmin=
if test -z "$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
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
