Streams (stderr, stdin, stdout)

stdin

Standard In. Whatever is entered into the bash terminal

stdout

Standard Out. Whatever output was given back by the terminal.

stderr

Standard Error. Whatever error was given back by the terminal

Redirect stderr to /dev/null

You can redirect the stderr to /dev/null to get rid of it. You don’t care if there are errors, you don’t want to see those errors, you don’t want to log those errors, you just want them gone.

1ls avdkaeudvaev 2>> /dev/null

Save both stderr and stdout

1ls fileThatExists fileThatDoesNotExist > mystdoutput 2> mystderror

will save the stdout in a file called mystdoutput and save the stderr in a file called mystderror. We will get both stdout and stderr because we are listing a file that exists (stdout) and a file that doesn’t exist which will result in an error (stderr). One command, one entry, two separate files.

Uses:

• in bash scripts, you can supress outputting errors and log them to an error log instead.

/dev/null

/dev/null is nothing. It’s a black hole. When you are redirecting something to /dev/null, you are basically telling it to get lost. And it will, get lost, in the nothnigness.