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From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: shortest self-reproducing Perl program
Message-ID: <7490@jpl-devvax.JPL.NASA.GOV>
Date: 20 Mar 90 23:47:29 GMT
References: <1990Mar20.203516.8429@iwarp.intel.com>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 44

In article <1990Mar20.203516.8429@iwarp.intel.com> merlyn@iwarp.intel.com (Randal Schwartz) writes:
: Okay, here's my entry for the shortest self-reproducing Perl program.
: Any takers for shorter?  Any one liners?
: 
: print<<'E'x 2,"E\n";
: print<<'E'x 2,"E\n";
: E
: 
: The program must be fed to an unadorned Perl command 'perl' and
: produce the output that would make 'perl' look like it has been
: replaced with 'cat'.  The null program is not a valid submission.  (I
: claim it first... :-)

An obvious abridgement is to delete all the E's:

print<<''x 2,"\n";
print<<''x 2,"\n";


Note the blank line at the end.  A not-so-obvious improvement is that
the last semicolon is now optional.  (For shame!  You of all people
should have thought of this one, Randal!)

print<<''x 2,"\n"
print<<''x 2,"\n"


It's too bad you said the thing about cat.  Otherwise

die<<''x 2."\n"
die<<''x 2."\n"


would qualifiy.

But, we can shorten the "\n" by two characters:

print<<''x 2,$/
print<<''x 2,$/


I haven't thought about one liners yet.

Larry