echo命令

•概述
用於在shell中打印shell變量的值，或者直接輸出指定的字符串。
•選項
-n：不進行換行
-e：讓轉義符生效
\n：換行
\t：製表符
STRING可以使用引號，單引號和雙引號均可用
單引號：強引用，變量引用不執行替換
~]# echo '$SHELL'
雙引號：弱引用，變量引用會被替換
~]# echo "$SHELL"
注意：變量引用的正規符號
${name}
•實例
[root@localhost ~]# echo how are you doing.How do you do?
how are you doing.How do you do?
[root@localhost ~]# echo -e "how are you doing.\tHow do you do?"
how are you doing. How do you do?
[root@localhost ~]# echo -e "how are you doing.\nHow do you do?"
how are you doing.
How do you do?