Shulou(Shulou.com)06/02 Report--

Today, I will talk to you about how to use the echo command in the linux system. Many people may not know much about it. In order to make you understand better, the editor has summarized the following for you. I hope you can get something according to this article.

Basics

The echo command is often used as a printout string, and the following information can be obtained from the echo help file:

Syntax echo [- neE] [arg...]

Three parameters:

-n: automatic line wrapping when output text is turned off

-e: enable escape character function (\)

-E: (default) turn off the escape character function (\)

When using the-e option, if you type the following characters into a string, the program does not output it as a normal string, but uses its escape function:

\ a sound of warning

\ b Delete the previous character

\ c output after no newline symbols are added and characters are suppressed

\ f Wrap line, but the cursor remains in its original position

\ nWrap and the cursor moves to the beginning of the line

\ r move the cursor to the beginning of the line, but do not wrap

\ t horizontal tabs

\ v Vertical tab character

\ insert\ character

\ 0nnn inserts ASCII characters represented by nnn (octal); NNN is 0 to 3 octal digits

\ xHH inserts ASCII characters represented by HH (hexadecimal); HH is 1 to 2 hexadecimal digits

Example

1. Print out a line of string

2. Use the "\ b" option

Equivalent to backspace character

3. Use the "\ c" option

Characters after\ c are not printed, and the result does not wrap (use the-n option only to output the result without wrapping)

4. Use the "\ n" option

It is equivalent to inserting a new row after\ n

5. Use the "\ r" option

Enter, move the cursor to the first position, but do not wrap

6. Use the "\ 0NNN" option

Returns ASCII characters represented by octal multi-representation

7. Use the "\ xHH" option

Returns the ASCII character represented by the hexadecimal number

8. Printout bash environment variables

Extend:

Single quotation mark "; double quotation mark"; reverse single quotation mark "quotation strength comparison

From the running results, it is not difficult to see that "single quotation marks are strong references and do not complete variable substitution;" reverse single quotation marks are weak references, which can realize command and variable substitution; "" double quotation marks are strong and weak, according to the middle of the two, only variable substitution can be realized.

After reading the above, do you have any further understanding of how to use the echo command in the linux system? If you want to know more knowledge or related content, please follow the industry information channel, thank you for your support.

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