https://www.baeldung.com/linux/dash-in-command-line-parameters

The “-” in the above command is actually an alias for /dev/stdin. Therefore, we can also replace the “-” with /dev/stdin, and nothing will change:

Well, /dev/stdin is a symbolic link to /proc/self/fd/0. The /proc/self/fd/0, in turn, is a symbolic link to the standard input of our current shell process, which is our terminal.