It is called "process substitution", and can work the other way around: http://www.tldp.org/LDP/abs/html/process-sub.html http://www.tldp.org/LDP/abs/html/proc

It is called "process substitution", and can work the other way around: http://www.tldp.org/LDP/abs/html/process-sub.html http://www.tldp.org/LDP/abs/html/process-sub.html With fish: https://fishshell.com/docs/current/commands.html#psub https://fishshell.com/docs/current/commands.html#psub But there it only works one way: https://github.com/fish-shell/fish-shell/issues/1786 https://github.com/fish-shell/fish-shell/issues/1786