echo命令

•概述
用于在shell中打印shell变量的值，或者直接输出指定的字符串。
•选项
-n：不进行换行
-e：让转义符生效
\n：换行
\t：制表符
STRING可以使用引号，单引号和双引号均可用
单引号：强引用，变量引用不执行替换
~]# echo '$SHELL'
双引号：弱引用，变量引用会被替换
~]# echo "$SHELL"
注意：变量引用的正规符号
${name}
•实例
[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?