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To stderr: >&2

graph LR A[Command Output] -->|stdout| B((stdout)) A -->|stderr| C((stderr)) B -.->|Redirect stdout to stderr| C

The >&2 syntax in shell scripting is used to redirect standard output (stdout) to standard error (stderr). In the context of Bash or another shell, file descriptor 1 represents stdout, and file descriptor 2 represents stderr. Redirecting output is a common practice for managing where output from commands is sent, allowing for more precise control over logging and error handling.

Here's a breakdown of >&2:

  • > is the redirection operator, used to direct the output from a command to somewhere other than its default destination (which is usually the terminal screen).
  • & indicates that what follows is a file descriptor, not a filename.
  • 2 is the file descriptor for standard error.

So, when you see >&2, it means "redirect the output (from stdout) to stderr."

This can be useful in several contexts, such as when you want error messages or diagnostics to be sent to stderr instead of mixing them with the regular output of your script or program, which goes to stdout. This separation allows for better handling of errors and output, especially when logging or when you're piping the output of your script to another command.

Here's a simple example:

echo "This is an error message" >&2

This command will send the string "This is an error message" to stderr instead of stdout. If you're running a script from a terminal, you might not notice the difference because both stdout and stderr typically display on your screen. However, if you redirect or capture the outputs separately, the distinction becomes clear and useful for processing output and errors differently.

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