I've just come across
!$ (without quotes). I've not met this before and did some tests:
$ ls -l (...some output...) $ echo !$ -l $ echo "!$" -l
man bash says this in the section on history expansion:
$ The last word. This is usually the last argument, but will expand to the zeroth word if there is only one word in the line.
Fair enough. But should I quote it or not? Another test on history expansion leaves me in doubt:
$ man bash $ "!!" "man bash" bash: man bash: command not found
This could be expected. But then, what about
!$? This is one word, so I guess it should be quoted...
(I'll risk this new tag here: good-practice.)