What means dev null 2>& 1?

What means dev null 2>& 1?

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 .

How to redirect stderr and stdout 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 it mean 2>/ dev null?

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. By default they are printed out on the console. \> redirects output to the specified place, in this case /dev/null.

What does || mean in shell script?

Just like && , || is a bash control operator: && means execute the statement which follows only if the preceding statement executed successfully (returned exit code zero). || means execute the statement which follows only if the preceding statement failed (returned a non-zero exit code).

How do I redirect everything to Dev Null?

You can use dd for this, but dd either outputs to stdout or can be instructed to write to a file. With of=/dev/null you can tell dd to write to this virtual file. You don’t even have to use shell redirections here.

How do I suppress stderr output?

To hide the standard error (stderr) or standard output (stdout) messages produced by a program, redirect them to /dev/null, a special file that swallows all data written to it.

How do I redirect stderr to stdout?

Redirecting stderr to stdout When saving the program’s output to a file, it is quite common to redirect stderr to stdout so that you can have everything in a single file. > file redirect the stdout to file , and 2>&1 redirect the stderr to the current location of stdout . The order of redirection is important.

How do I redirect stderr to a file?

To redirect stderr as well, you have a few choices:

1. Redirect stdout to one file and stderr to another file: command > out 2>error.
2. Redirect stdout to a file ( >out ), and then redirect stderr to stdout ( 2>&1 ): command >out 2>&1.

How to redirect only the stderr file to /dev/null?

The file specified in this case is /dev/null. Hence, the data is ultimately discarded. If any other file were given instead of /dev/null, the standard output would have been written to that file. Similarly, to redirect only the STDERR to /dev/null, use the integer ‘2’ instead of ‘1’. The integer ‘2’ stands for standard error.

What does redirected to /dev/null mean?

redirects stderr and stdout to /dev/null… which means to nowhere. Things sent to /dev/null are not saved, cached, or remembered in any way. They are just sent to ‘ nowhere ‘ and forgotten. This is a way of running programs and making sure they produce NO output and will never be seen on the command line or in a log file.

How to discard stdout and stderr at the same time?

Similarly, to redirect only the STDERR to /dev/null, use the integer ‘2’ instead of ‘1’. The integer ‘2’ stands for standard error. As you can see, the standard error is not displayed on the terminal now as it is discarded in /dev/null. Finally, to discard both STDOUT and STDERR at the same time, use the following: