test.sh
#!/bin/bash
echo "enter the string:"
read filename
if test -z $filename ; then
echo "the length is 0"
else
echo "the length is not 0"
fi
执行
sudo chmod +x test.sh
./test.sh
输出
enter the string: the length is
执行
./test.sh
输出
enter the string:
sssssss
the length is not