echo 換行不換行

echo換行輸出需要轉義符 -e

看以下例子：

echo -e "It is the first line." >> a; echo -e "It is the second line.\c" >> a; echo -e "It is the third line." >> a; echo -e "\nIt is the forth line." >> a

輸出：

It is the first line.                                   //默認換行
It is the second line.It is the third line.             //第二行指定不換行，因此第三行緊跟第二行
                                    
It is the forth line.                                  //第三行默認換行，而且第四行前制定換行，因此中間空了一行