shell 判断字符串长度是否不为0

test.sh

#!/bin/bash
s1=""
if test $s1 ;then
echo "length is not zero"
else
echo "the length is 0"
fi
s2="shell"
if test $s2 ;then
echo "length is not 0"
else
echo "the length is 0"
fi

执行

sudo chmod +x test.sh
./test.sh

输出

the length is 0
length is not 0