echo
-e 代表後面會執行跳脫字元像是 \n，-n 則會略過printf format-string [arguments…]
format-string: 輸出的格式定義
arguments: 參數清單| 格式定義 | 說明 |
| \” | double quote |
| \\ | backslash |
| \a | alert (BEL) |
| \b | backspace |
| \c | produce no further output |
| \e | escape |
| \f | form feed |
| \n | new line |
| \r | carriage return |
| \t | horizontal tab |
| \v | vertical tab |
| \NNN | byte with octal value NNN (1 to 3 digits) |
| \xHH | byte with hexadecimal value HH (1 to 2 digits) |
| \uHHHH | Unicode (ISO/IEC 10646) character with hex value HHHH (4 digits) |
| \UHHHHHHHH | Unicode character with hex value HHHHHHHH (8 digits) |
| %% | a single % |
| %b | ARGUMENT as a string with ‘\’ escapes interpreted, except that octal escapes are of the form \0 or \0NNN |
| %q | ARGUMENT is printed in a format that can be reused as shell input, escaping non-printable characters with the proposed POSIX $” syntax. |