可以使用以下命令来判断文件是否为空：
test 命令：if [ -s filename ]; then
echo "File is not empty"
else
echo "File is empty"
fi
stat 命令：if [ $(stat -c %s filename) -eq 0 ]; then
echo "File is empty"
else
echo "File is not empty"
fi
wc 命令：if [ $(wc -c < filename) -eq 0 ]; then
echo "File is empty"
else
echo "File is not empty"
fi
