What is /dev/null and How to Use It

One such example is /dev/null. It's a special file that's present in every single Linux system. However, unlike most other virtual files, instead of reading, it's used to write. Whatever you write to /dev/null will be discarded, forgotten into the void. It's known as the null device in a UNIX system.

1. What is Dev Null used for?
2. What is the Dev Null and why would you use it?
3. How does Dev Null work?
4. What are the Dev Zero and Dev Null typically used for?
5. Can you read from Dev Null?
6. What does 2 Dev Null mean?
7. Is there a dev null in Windows?
8. How do I send stdout to Dev Null?
9. What is tail Dev Null?
10. How do I send error to Dev Null?
11. What does >/ dev null 2 >& 1 mean?
12. What is a null driver?

What is Dev Null used for?

< /dev/null is used to instantly send EOF to the program, so that it doesn't wait for input ( /dev/null , the null device, is a special file that discards all data written to it, but reports that the write operation succeeded, and provides no data to any process that reads from it, yielding EOF immediately).

What is the Dev Null and why would you use it?

To begin, /dev/null is a special file called the null device in Unix systems. Colloquially it is also called the bit-bucket or the blackhole because it immediately discards anything written to it and only returns an end-of-file EOF when read.

How does Dev Null work?

/dev/null is a special type file known as a character device file. This means that the file acts like a device that is unbuffered and can accept streams of data. Any data written to /dev/null is discarded. However, the write operation will return successful.

What are the Dev Zero and Dev Null typically used for?

"/dev/zero" and "/dev/null" are two dummy devices files which are useful for creating empty files. "/dev/zero": It is used to create a file with no data but with required size(A file with all zero's written on it). it creates a file that has continuous zeros in it.

Can you read from Dev Null?

You write to /dev/null every time you use it in a command such as touch file 2> /dev/null. You read from /dev/null every time you empty an existing file using a command such as cat /dev/null > bigfile or just > bigfile. Because of the file's nature, you can't change it in any way; you can only use it.

What does 2 Dev Null mean?

Specifying 2>/dev/null will filter out the errors so that they will not be output to your console. In more detail: 2 represents the error descriptor, which is where errors are written to. ... /dev/null is the standard Linux device where you send output that you want ignored.

Is there a dev null in Windows?

This device is called /dev/null on Unix and Unix-like systems, NUL: (see TOPS-20) or NUL on CP/M and DOS (internally \DEV\NUL ), nul on newer Windows systems (internally \Device\Null on Windows NT), NIL: on Amiga operating systems, and NL: on OpenVMS. In Windows Powershell, the equivalent is $null .

How do I send stdout to Dev Null?

Redirect All Output to /dev/null

There are two ways to do this. The string >/dev/null means “send stdout to /dev/null,” and the second part, 2>&1 , means send stderr to stdout. In this case you have to refer to stdout as “&1” instead of simply “1.” Writing “2>1” would just redirect stdout to a file named “1.”

What is tail Dev Null?

4. @Sokre - The tail -f /dev/null is a common idiom for keeping a container alive indefinitely if the "real" command isn't long-lived. –

How do I send error to Dev Null?

In Unix, how do I redirect error messages to /dev/null? You can send output to /dev/null, by using command >/dev/null syntax. However, this will not work when command will use the standard error (FD # 2). So you need to modify >/dev/null as follows to redirect both output and errors to /dev/null.

What does >/ dev null 2 >& 1 mean?

2>&1 redirects standard error to standard output. &1 indicates file descriptor (standard output), otherwise (if you use just 1 ) you will redirect standard error to a file named 1 . [any command] >>/dev/null 2>&1 redirects all standard error to standard output, and writes all of that to /dev/null .

What is a null driver?

You might install a "null driver" (that is, nonexistent driver) for a device if the device is not used on the machine and should not be started. Such devices do not typically exist on a machine, but if they do, you can install a null driver.