#!usr/bin/perl
use warnings;
use strict;

my @text;
{
    local @ARGV = ( './contents' );

    while ( <> ) {
        push @text, grep /important/, $_;
    }
}

print @text, "\n";
print @ARGV, "\n";

##</code><code>##

#!usr/bin/perl
use warnings;
use strict;

sub contents {
    local @ARGV = @_;
    return my @t = <>;
}

my $text;
$text = contents 'contents2';
print $text . "\n";

my @text = grep /important/, contents 'contents2';
print @text, "\n";
print @ARGV, "\n";

##</code><code>##

#!usr/bin/perl
use warnings;
use strict;

sub contents {
    local @ARGV = @_;
    <>;
}

my $text;
$text = contents 'contents3';
print $text . "\n";

my @text = grep /important/, contents 'contents3';
print @text, "\n";
print @ARGV, "\n";

##</code><code>##

#!usr/bin/perl
use warnings;
use strict;

my @text;
while ( <> ) {
    push @text, grep /important/, $_;
}

print @text, "\n";
print @ARGV, "\n";

##</code><code>##

#!usr/bin/perl
use warnings;
use strict;

unless ( defined $ARGV[0] ) {
    die "Usage: contents4 <filename>\n";
}

my @text;
{
    local @ARGV = ( $ARGV[0] );

    push @text, grep /important/, <>;
}

print @text, "\n";
print @ARGV, "\n";

##</code><code>##

#!usr/bin/perl
use warnings;
use strict;

sub grepfile {
    local @ARGV = ( $_[1] );
    return grep /$_[0]/, <>;
}

my @text = grepfile 'important', './grepfile';
print @text, "\n";
print @ARGV, "\n";