Re: lwall snippet

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   Date: Sun, 11 Apr 2004 03:56:16 +0200
   From: "A. Pagaltzis" <[email protected]>
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   * Etienne Grossmann <[email protected]> [2004-04-11 03:19]:
   > On Sat, Apr 10, 2004 at 08:56:26PM -0400, [email protected] wrote:
   > >   last|perl -pe '$_ x=/(..:..)...(.*)/&&"'$1'"ge$1&&"'$1'"lt$2'
   > >   That's gonna be tough for Randal to beat...  :-)
   > >            -- Larry Wall in  <[email protected]>
   > 
   > The other conditions in the rhs I don't grok.

   Remember that it's shell code at the first iteration here, and as
   there's single-quotes in the middle of the Perl code, only the
   following bits are seen verbatim by Perl:

       perl -pe '$_ x=/(..:..)...(.*)/&&"'$1'"ge$1&&"'$1'"lt$2'
		 ^^^^^^^^^^^^^^^^^^^^^^^^    ^^^^^^^^    ^^^^^

   The rest is interpreted by the shell -- particularly, the $1 and
   $2 not protected by anything are interpolated before Perl is even
   called.

   With a little spacing, the code reads like this:

       $_ x= /(..:..)...(.*)/ && 'foo' ge $1 && 'bar' lt $2;

   where I'm assuming that the shell's $1 was "foo" and its $2 was
   'bar'.

I see.  But I think you meant

       $_ x= /(..:..)...(.*)/ && 'foo' ge $1 && 'foo' lt $2;

since the shell's $2 is never used, as far as I can tell.  I still
have no clue what the shell's $1 would be in this case, other than the
empty string.

kj