What does 2 >& 1 at the end of a command do?
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 is standard input output in Linux?
The Linux Standard Streams In Linux, stdin is the standard input stream. This accepts text as its input. Text output from the command to the shell is delivered via the stdout (standard out) stream. Error messages from the command are sent through the stderr (standard error) stream.
What does the 2 >& 1 at the end of the following command mean LS names 2 >& 1?
It means redirect the output of stderr (file descriptor 2) to stdout (file descriptor 1).
How do I get standard input in Linux?
A simple example is provided by the wc command, whose default behavior is to count the number of lines, words and characters in text. Typing this command in at the command line and pressing the ENTER key to start a new line allows any text subsequently entered at the keyboard to become the standard input for wc.
What are the 3 standard streams in Linux?
There are 3 type of standard streams; standard input (stdin), standard output (stdout) and standard error (stderror).
What does the 2 >& 1 at the end of the following command mean ls names 2 >& 1?
What is the standard input output and error file in Linux?
Working with Standard Input, Output and Errors in Linux. Every process in Linux is provided with three open files( usually called file descriptor). These files are the standard input, output and error files. By default : Standard Input is the keyboard, abstracted as a file to make it easier to write shell scripts.
What is the output of the a command in Linux?
A command normally reads its input from the standard input, which happens to be your terminal by default. Similarly, a command normally writes its output to standard output, which is again your terminal by default.
How to redirection output in Linux/Unix?
Input Output Redirection in Linux/Unix Examples. 1 Output Redirection. The ‘>’ symbol is used for output (STDOUT) redirection. Here the output of command ls -al is re-directed to file “listings” 2 Input redirection. 3 File Descriptors (FD) 4 Error Redirection. 5 Why Error Redirection?
What does “2>&1” mean in Linux?
1. In the below-mentioned example, the file descriptor used above is 2 (STDERR). Using “ 2> ” re-directs the error output to a file named “error.txt” and nothing is displayed on STDOUT. 2. Here, 2>&1 means that STDERR redirects to the target of STDOUT. More formally, the error message generated by “ 2 ” gets merged with the current output “ 1 “.