2011w39

Stupid shell tricks

A friend of mine asked me this week how one would go about repeating the same command X number of times in a shell.

My first idea was of course a for-loop, along the lines of:

X=15; for i in $(seq 1 ${X?}); do echo "foo bar baz"; done

But his reply to that suggestion was that seems a bit much if all I want is to repeat the command twice…

Ok, so it wasn’t for X equalling any number, it was for X equalling two… sometimes I get the feeling that he is perhaps over-generalizing his questions to me ;D

Anyway, my second answer, given this new input, was: What? You’re too lazy to execute it, push up-arrow and enter?

But of course, his question had already caused me to fork a background process intent on finding a solution.

First I thought about the history command, and I ultimately came up with a solution through reading man history.

echo "foo bar baz"; !#

Note: That semicolon there is frakking important!

“!” when issued as the first char of a new word, should be interpreted as we’re going to do something with the history of this shell.

“#” in turn could roughly be interpreted as On this current line, do again whatever has been done from the start of this line, to where this history command is called

The result is echo “foo bar baz”; echo “foo bar baz”;

I have no idea what he needed that for, it seems pretty limited to me, but either way it’s pretty cool that it worked.

Now guess what echo "foo bar baz"; !# !# does.

How to get into Free Software

A buddy from work and I spoke about open source and free software the other day, and he had a basic grasp about it, but what he felt he lacked were knowledge of useful sites, etc. I.e. perhaps not how to become more involved, he’d already submitted patches to some specific projects, but more along the lines of where likeminded “hang out”?

That’s a poor description as well, and isn’t all that important. It did however get me thinking about it.

There is identi.ca instead of twitter, joindiaspora.com instead of facebook or google+. There is fsf.org, gnu.org and fsfe.org as well as the local (Swedish) ffkp.se for information about the ideology behind free software, but also for information about how to get involved and the types of activism they engage in.

I don’t really know how to categorize ohloh.net, but I guess it could be a fun place to hang out and either get recognition for your own contributions, or recognize the projects you use yourself.

Then I guess there is the part of the FOSS ecosystem which ?doesn’t exist at all? in the proprietary world (I am sure there are some exceptions to this) such as public code repository sites (savannah.{,non}gnu.org, gitorious as well as github and bitbucket).

I have accounts on all four, although I make a conscious effort to prefer the first two services over the latter two.

And then of course there are conferences which one could attend, FSCONS (yes, being biased, I put the one I’m co-organizing first) and FOSDEM springing immediately to mind.

Links

Another Humble Indie Bundle in the making. This game looks like it would be precisely my type of thing. Maybe ;)

This Erlang “hello, world!” tutorial has definitively earned itself some linklove.

:wq

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2 Responses to “2011w39”

  1. Of course he balked at the complexity of the for loop you originally gave, bash is willing to bear some of the load for you:

    for i in {1..15}; do echo “foo bar baz”; done

    This is definitely simpler, but still may be a little much for 2 runs.

  2. Patrik says:

    Heya!

    Nice!
    I didn’t even think of that one :/

    But yes, still a little verbose for just two runs.

    Cheers,
    Patrik