Article 4874 of comp.lang.perl:
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From: Tom Christiansen <tchrist@cs.Colorado.EDU>
Subject: Re: Conversion /etc/passwd --> /usrc/lib/aliases ?
Message-ID: <1993Aug10.101001.28845@colorado.edu>
Followup-To: comp.lang.perl
Originator: tchrist@wraeththu.cs.colorado.edu
Sender: news@colorado.edu (The Daily Planet)
Nntp-Posting-Host: wraeththu.cs.colorado.edu
Reply-To: tchrist@cs.colorado.edu (Tom Christiansen)
Organization: University of Colorado, Boulder
References: <247i8p$7gi@rwa.urc.tue.nl>
Date: Tue, 10 Aug 1993 10:10:01 GMT
Lines: 82

[Note followup-to, which may or may not be appropriate.]

From the keyboard of tgcpwd@rwa.urc.tue.nl (Wim van Dorst/Prof. Penninger):
:I know there is a nifty little program (shell/perl script?) that turns the 
:Personal Name information in the /etc/passwd file into /usr/lib/aliases
:entries for mail programs.  This will greatly enhance mail addressing
:for the particular machine.
:
:E.g. the line from /etc/passwd
:
:	duck:2QaBd4:321:20:Harold Wilberforce Clifton:/home/duck:/bin/sh
:
:would become the entries in /usr/lib/aliases for
:
:	clifton:	duck
:	harold:	duck
:	harold.clifton:	duck
:	harold.wilberforce.clifton:	duck
:	h.clifton:	duck
:	h.w.clifton:	duck
:	harold.w.clifton:	duck
:	etc.
:
:Thus instead of only being able to do 'duck@what.ever', one can
:address this same person with the more comprehensible, and thus more
:memorizable, 'harold.w.clifton@what.ever'.
:
:Where can I find the program that does this? I thought it might be in
:the Elm 2.4.22 distribution, in Smail 3.1.28, or in Perl 4.036, but it 
:seems it is not. Then where _is_ it? Or could a person, knowledgeable
:in the field of probably Perl, do up such a script for me, please?

Well, that's a pretty easy script to write, but what are you going to 
do about conflicts?  Lots of people have the same first name?  

Here's a brute force method that pretty much works:

    #!/usr/bin/perl

    while (@pw = getpwent()) {
	($login, $gcos) = @pw[0,6];
	$gcos =~ s/,.*//;		# phone information
	$gcos =~ s/&/\u\L$login/g;	# the dreaded & hack
	$gcos =~ s/\.//g; 		# can't add too many dots

	@names = split(' ', $gcos);
	next unless @names > 0;

	&alias($names[0]);

	next unless @names > 1;

	&alias($names[$#names]);
	&alias(join ('.', $names[0], $names[$#names]));
	&alias(join ('.', substr($names[0],0,1), $names[$#names]));

	next unless @names > 2;

	&alias(join ('.', @names));

	&alias(join ('.', $names[0], substr($names[1],0,1), $names[$#names]))
	    if length($names[1]) > 1;

	&alias(join ('.', substr($names[0],0,1), substr($names[1],0,1),
			    $names[$#names]))
	    if length($names[1]) > 1 && length($names[2]) > 1;

    } 

    sub alias {
	local($alias) = "\L$_[0]";
	return if $alias eq $login;

	if ($seen{$alias}) {
	    warn "$alias already aliased to $seen{$alias}\n";
	} else {
	    $seen{$alias} = $login;
	} 

	print "$alias: $login\n";
    } 




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