My extremely short shell cheatsheet for things I do rarely enough to forget each time:

    Process substitution:
        bash: diff <(echo hello) <(echo world)
        fish: diff (echo hello | psub) (echo world | psub)
    
    Rsync directories:
        rsync -a -v --dry-run other:dir/ dir/
        Syncs the contents of dir (`/` needed)
    
    Script exit handler:
    bash:
        function finish {
          # exit handling code
        }
        trap finish EXIT # EXIT is special and works on normal exit as well as interrupts