This should work fine on Windows right out of the box, but for Linux you may need to install xclip.
sudo apt-get install xclip
I keep finding myself in situations where I need to copy the content of a file or curl output and so on, and I don't like having to use the mouse when I'm in a terminal. So now this exists.
qcopy /path/to/file.txt
Linux
curl https://givemea.io/random/number/1000 > qcopy
Windows
Invoke-RestMethod https://givemea.io/user/5 | ConvertTo-Json | qcopy
This turned out to be far easier than I expected it to be, thanks to Pyperclip. Thanks for basically doing all the work for me.