What is the meaning of 2 &1 in Linux?

&1 is used to reference the value of the file descriptor 1 (stdout). Now to the point 2>&1 means “Redirect the stderr to the same place we are redirecting the stdout” Now you can do this. What does 1 & 2 mean in shell script?

File descriptor 1 is stdout and File descriptor 2 is stderr . Using > to redirect output is the same as using 1> . This says to redirect stdout (file descriptor 1). Normally, we redirect to a file.

What does the 2 >& 1 at the end of the following command mean?

means redirection. &1 means the target of the redirection should be the same location as the first file descriptor, i.e. stdout . So > /dev/null 2>&1 first redirects stdout to /dev/null and then redirects stderr there as well. This effectively silences all output (regular or error) from the wget command.

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 2 and1 batch file?

The 2 denotes standard error (stderr). So 2>&1 says to send standard error to where ever standard output is being redirected as well. Which since it’s being sent to /dev/null is akin to ignoring any output at all.

What does 2 mean in shell?

37. File descriptor 2 represents standard error. (other special file descriptors include 0 for standard input and 1 for standard output). 2> /dev/null means to redirect standard error to /dev/null . /dev/null is a special device that discards everything that is written to it.

Why do we use 2 >> redirection?

You can use &[FILE_DESCRIPTOR] to reference a file descriptor value; Using 2>&1 will redirect stderr to whatever value is set to stdout (and 1>&2 will do the opposite).

What is the meaning of 2 >& 1 in Linux?

&1 is used to reference the value of the file descriptor 1 (stdout). Now to the point 2>&1 means “Redirect the stderr to the same place we are redirecting the stdout”

What is Echo $1?

$1 is the argument passed for shell script. Suppose, you run ./myscript.sh hello 123. then. $1 will be hello. $2 will be 123.

What does >> mean in command line?

58. >> can be used to pipe output into a text file and will append to any existing text in that file. ‘any command’ >> textfile.txt. appends the output of ‘any command’ to the text file.

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

Is Dev null a file?

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 do I redirect a cron job?

To do this, modify the crontab entry and add the output and error redirection as shown below. In the above: > /home/john/logs/backup. log indicates that the standard output of the backup.sh script will be redirected to the backup.