The following snippet should work on every system that has coreutils.
$ shuf /usr/share/dict/words --repeat --random-source /dev/random -n 5
You can swap /usr/share/dict/words with any good wordlist, like EFF’s or Arnold Reinhold’s Diceware list.
You can also add it for ease of use to your ~/.bash_aliases
alias passphrase="shuf ~/dotfiles/misc/diceware8k.txt --repeat --random-source /dev/random -n"
And then you could easily use it in bash:
$ passphrase 5
notch
kane
to
drag
cater