`2>&1` notation is used to redirect standard error output (`stderr`) to standard output (`stdout`) and have these outputs combined in `stdout`. In this notation, `2` is a `stderr` file descriptor and `1` is a `stdout`. `&` sign is used to distinguish **file descriptors** from file names. Otherwise `2>1` would be interpreted as `stderr` redirection to file called „1”. ### See also 1. [[What is file descriptor?]] ### Reference 1. [Useful Post on superuser.com](https://superuser.com/questions/71428/what-does-21-do-in-command-line)