[ale] Bash scripting q

[Warren Myers]

How about:

#!/bin/sh
USER=$1
cp foo `~$USER`
chown $USER `$USER/foo`

On Thu, May 8, 2008 at 3:38 PM, JK <jknapka at kneuro.net> wrote:

> Hi folks,
>
> I am trying to do a very simple thing, and getting screwed by bash's
> evaluation
> rules.  Basically, I need to write a script that accepts a user name,
> and then
> copies some files to that user's home dir, and also chowns them to that
> user.
> So I tried the obvious:
>
> #!/bin/bash
> USER=$1
> cp foo  ~$USER
> chown $USER ~$USER/foo
>
> This totally fails to work as I expect, because tilde expansion happens
> before variable expansion.  So if I supply 'joe' as the first arg, "~$USER"
> expands to ~joe (instead of the desired /home/joe), and the cp effectively
> evaluates to "cp foo '~joe'", which ends up creating a regular file named
> ./~joe
>
> Is there a clean workaround?  I'd rather not force the user to supply both
> the user name and the user's home directory as script arguments.  And
> doing a grep'n'cut on /etc/passwd is not too appealing either.  I've
> checked
> a couple of books ("bash Cookbook", "Linux Shell Scripting", and an
> online tutorial or two), but the most any of them say is "Don't do that";
> they provide no workaround.
>
> An explicit command to force shell expansion of an arbitrary string would
> do the trick... I'm goofing around with echo and eval right now, with
> interesting, but not useful, results...
>
> Oops, just stumbled on an answer:
>
>  cp foo $(eval echo $(echo ~$USER))
>
> works, although it makes my eyes water a bit.  Is there a better way?
> (This post has devolved to the "Linux trivia quiz" level...)
>
> Thanks,
>
> -- Joe
>
> --
> I do not particularly want to go where the money is -
>  it usually does not smell nice there. -- A. Stepanov
>
>
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>



-- 
http://warrenmyers.com
"God may not play dice with the universe, but something strange is going on
with the prime numbers." --Paul Erdős
"It's not possible. We are the type of people who have everything in our
favor going against us." --Ben Jarhvi, Short Circuit 2
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