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You mean "$_". !$ refers to the previous command in the history.

!! refers to the previous command in the history. !$ refers to the last cmd-line option in the history.

I know that, the bit I want to emphasize is that it won't be the mkdir argument that is on the same line.

Fairly sure I meant !$ :)

http://www.gnu.org/software/bash/manual/bashref.html#Word-De...

Seriously, try it. History expansion works on input lines separated by the user asking the shell to run them, it can't cross reference command arguments on the same command line.

I have tried both, the difference is only that !$ echos the expanded command, while $_ simply runs the expanded command; both create a directory and cd into it.

(I'm running OS X, FWIW)

You are correct, so have an upvote.

&& in OS X seems to put the left side into history and works as I described, but it didn't work when I tried it in Ubuntu 10. $_ works in both.

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