Re: difference between these lines

On 29 June 1998, Walter Torres <walter(_at_)tscinternet(_dot_)com> wrote:
> Can anyone tell me the difference between these two lines?
>
> MAILDIR=$HOME/mail/
>
> and
>
> MAILDIR=${MAILDIR:-$HOME}
>
> Both of these were found on .procmailrc files in 2 different accounts.
    "What's the difference between a hammer and a screwdriver?  Both
of these were found in two different tool boxes".  (Sorry, I couldn't
resist).

    Well, let's see: the first sets $MAILDIR to point to the mail/
directory in your $HOME; the second looks at $MAILDIR, and if it's not
set (or if it's set to an empty value) it sets it to $HOME, otherwise
it leaves it alone.  Try "man sh" to find out more about ${...}
substitutions.

    Regards,

    Liviu

-- 
Dr. Liviu Daia                   e-mail:   daia(_at_)stoilow(_dot_)imar(_dot_)ro
Institute of Mathematics         web page: http://www.imar.ro/~daia
of the Romanian Academy          PGP key:  finger 
daia(_at_)stoilow(_dot_)imar(_dot_)ro