Sometimes I want to quickly copy the contents of a file, e.g. when I'm creating a new SSH key.
Up until now, I would use
cat to read the content, then select it and finally copy it.
$: cat id_rsa.pub ssh-rsa AAAAB3NzaC1y...
You can do it much faster, using pbcopy, which copies the file content directly to the clipboard.
pbcopy < id_rsa.pub
Note, that, as the title of this post suggest,
pbcopy is available only on Mac OS. For Linux, you might want to check xclip.