For interacting with the clipboard on GNU/Linux, I use xsel and xclip. The former is more concise, but the latter provides some useful features.
For example, `xsel` to read primary, `xsel -b` for what most users know as the clipboard, `-i` for writing. `xsel | xsel -ib` to copy from primary to clipboard.
`xclip -l 1 -quiet` to block until one paste. Useful to e.g. pipe a password from a password manager so that it gone after you paste it, or to chain pastes (user then pass).
I used a password manager and more as examples of xsel/xclip in my LibrePlanet 2019 talk:
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