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Date: Sun, 01 Mar 2015 08:07:16 -0800
From: Ray Andrews <rayandrews@eastlink.ca>
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To: zsh Users <zsh-users@zsh.org>
Subject: grammar triviality with '&&'
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I notice that zsh is quite tolerant as far as most
line wrap situations go, except for this:

     [ -e file1 ] &&
     [ -e file2 ] &&
     echo 'both files exist'

... good

     [ -e file1 ]
     && [ -e file2 ]
     && echo 'both files exist'

... syntax error, but we can fix it like this:

     [ -e file1 ]\
     && [ -e file2 ]\
     && echo 'both files exist'

I'm wondering why the line continuation is strictly necessary.
IOW, why doesn't the parser permit the '&&' on a new line?
I've been trying to come up with something that would
cause an ambiguity if it were permitted, but can't find anything,
but I doubt the rule would be there otherwise.