Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!zaphod.mps.ohio-state.edu!pacific.mps.ohio-state.edu!linac!convex!usenet
From: tchrist@convex.COM (Tom Christiansen)
Newsgroups: comp.lang.perl
Subject: Re: better head
Message-ID: <1991May17.172231.21193@convex.com>
Date: 17 May 91 17:22:31 GMT
References: <1991May16.152356.3186@convex.com> <1991May16.205446.15295@uunet.uu.net>
Sender: usenet@convex.com (news access account)
Reply-To: tchrist@convex.COM (Tom Christiansen)
Organization: CONVEX Software Development, Richardson, TX
Lines: 50
Nntp-Posting-Host: pixel.convex.com

From the keyboard of rbj@uunet.uu.net (Root Boy Jim):
:>    unshift(@ARGV, '-') unless $argc = @ARGV;  # <> changes @ARGV
:>    while (<>) {
:>	if ($. == 1 && $argc > 1) {
:>	    print "\n" if $deja_imprime++;
:
:It's deja vu all over again :-)

vraiment. :-)

:>	if ($. <= $num) {
:>	    print;
:>	} else {
:>	    close ARGV;
:>	} 
:
:I think you're reading too many lines.
:Wouldn't "print; close ARGV if $. == $num" be better?

I may be *reading* one line "too many", but at least 
the output is still right.

:I think you missed something tho.
:What happens if some of the files have less than $num lines?

It's true.  This works for those cases, too:

    #!/usr/bin/perl
    #
    # head -- perl clone of head command, but without head's silly 
    #	  limits regarding line lengths.  tchrist@convex.com

    $num = ($ARGV[0] =~ /^-(.+)/ && shift) ? $1 : 10; 
    die "$0: badly formed number: $1\n" unless $num =~ /^\d+$/;

    unshift(@ARGV, '-') unless $argc = @ARGV;  # <> changes @ARGV
    while (<>) {
	if ($. == 1 && $argc > 1) {
	    print "\n" if $deja_imprime++;
	    print "=> $ARGV <=\n" ;
	}
	print;
	close ARGV if $. == $num || eof;
    } 


--tom
--
Tom Christiansen		tchrist@convex.com	convex!tchrist
		"So much mail, so little time."