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?
&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 $$ in Linux?
$$ is the process ID (PID) of the script itself. $BASHPID is the process ID of the current instance of Bash. This is not the same as the $$ variable, but it often gives the same result.
What is 2 in bash script?
File descriptor 1 is stdout and File descriptor 2 is stderr . Using > to redirect output is the same as using 1> .
What is $2 in shell script?
$0 is the name of the script itself (script.sh) $1 is the first argument (filename1) $2 is the second argument (dir1) $9 is the ninth argument.
What does 1 mean in a text message?
1 means “Partner.”
What is the meaning of 1 by 4?
The fraction one-fourth, written in symbols as 1/4, means “one piece, where it takes four pieces to make a whole.” The fraction one-quarter, written in symbols as 1/4, means “one piece, where it takes 4 pieces to make a whole.”
What is $0 shell?
$0 Expands to the name of the shell or shell script. This is set at shell initialization. If Bash is invoked with a file of commands (see Section 3.8 [Shell Scripts], page 39), $0 is set to the name of that file.
What is if in bash script?
In bash scripting, as in the real world, ‘if’ is used to ask a question. The ‘if’ command will return a yes or no style answer and you can script the appropriate response.
What does 2 mean in terminal?
38. 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).
How do I redirect stderr?
To redirect stderr as well, you have a few choices:
- Redirect stdout to one file and stderr to another file: command > out 2>error.
- Redirect stdout to a file ( >out ), and then redirect stderr to stdout ( 2>&1 ): command >out 2>&1.