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When can you redirect to dev Null?
Other Examples Where It Can Be Useful to Redirect to /dev/null. Say you want to see how fast your disk can read sequential data. The test is not extremely accurate but accurate enough. You can use dd for this, but dd either outputs to stdout or can be instructed to write to a file.
How do I redirect error 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.
Why does stderr redirect to / dev / null?
STDERR redirects to THE ADDRESS of STDOUT (File descriptor 1 in that moment, or /proc/self/fd/1), and then STDOUT redirects to /dev/null , but STDERR keeps redirecting to fd1!! As a result the normal output from STDOUT is discarded, but the errors coming from STDERR are still being written onto the console.
Why does shell redirect to / dev / null?
This is because of using > /dev/null 2>&1 will redirect all your command output (both stdout and stderr) to /dev/null, meaning no outputs are printed to the terminal. To understand this easily, write it out explicitly.
Where does the data go in / dev / null?
Before diving deep into the usage of /dev/null, we have to have a clear grasp of the stdout and stderr data stream. Check out this in-depth guide on stdin, stderr, and stdout. Let’s have a quick refresh. Whenever any command-line utility is run, it generates two outputs. The output goes to stdout and the error (if generated) goes to stderr.
What happens when stdout is dumped to / dev / null?
Here, the contents of stdout are dumped to /dev/null, leaving only the errors. In certain situations, the output may not be useful at all. Using redirection, we can dump all the output into the void. Let’s break this command a little bit. First, we’re dumping all the stdout to /dev/null.