What is the 2 in Linux?

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.

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

The 1 denotes standard output (stdout). The 2 denotes standard error (stderr). So 2>&1 says to send standard error to where ever standard output is being redirected as well.

What does 2 mean in shell?

2 is a standard error (stderr) file descriptor. > is used for redirection. & indicates follow a file descriptor, not a file name. 1 is a standard output (stdout) file descriptor.

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

It means redirect any stderr ( 2> ) to the same place we are redirecting stdout ( &1 ). That’s right! ls myDir > result. txt 2>&1 is the same as ls myDir > result.

What is 2 dev Null in Linux?

After executing the ping command, ‘>/dev/null’ tells the system to suppress the output, and ‘2>&1’ directs the standard error stream to standard output. In this way, all output of the command is discarded.

What is $$ in Linux?

The $$ is the process id of the shell in which your script is running. For more details, see the man page for sh or bash. The man pages can be found be either using a command line “man sh”, or by searching the web for “shell manpage”

What is echo $1 Linux?

$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 Linux?

Logical AND operator
Logical AND operator(&&): The second command will only execute if the first command has executed successfully i.e, its exit status is zero. This operator can be used to check if the first command has been successfully executed. This is one of the most used commands in the command line.

What does $# mean in Linux?

the number of positional parameters passed
$# is the number of positional parameters passed to the script, shell, or shell function. This is because, while a shell function is running, the positional parameters are temporarily replaced with the arguments to the function.

What does 2 a out written at the end of a shell script signify?

1 “Standard output” output file descriptor. The expression 2>&1 copies file descriptor 1 to location 2 , so any output written to 2 (“standard error”) in the execution environment goes to the same file originally described by 1 (“standard output”).

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

What is 2 $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. /dev/null is the standard Linux device where you send output that you want ignored.

What is 2 Dev Null in Linux?

The N> syntax in Bash means to redirect a file descriptor to somewhere else. 2 is the file descriptor of stderr , and this example redirects it to /dev/null . What this means in simple terms: ignore error output from the command.

Why do we use 2 Dev Null?