What is the purpose of `2>&1`?

The 2>&1 construct is used in shell scripting and command-line interfaces to redirect error output (stderr) to the same location as standard output (stdout). Here's a breakdown of what it means:

• 2: This refers to the file descriptor for standard error (stderr).
• >&: This operator is used to redirect output.
• 1: This refers to the file descriptor for standard output (stdout).

When you use 2>&1, you are telling the shell to redirect stderr (file descriptor 2) to wherever stdout (file descriptor 1) is currently going.

For example, in the command:

command > output.txt 2>&1

• > output.txt redirects stdout to output.txt.
• 2>&1 then redirects stderr to the same location as stdout, which is now output.txt.

As a result, both standard output and standard error messages will be written to output.txt, allowing you to capture all output from the command in one file.