What is the Lebesgue measure of a line in $\mathbb R^2$? I am guessing that this zero. But i couldn't prove it rigorously. Please help... From this can i conclude that any proper subspace of $\mathbb R^n$ has measure zero.


Question: Find cron jobs that run between given times
Answer: Since this doesn't seem possible without parsing cron, I decided to write it myself in perl:
(not sure why the formatting is fubar)

#!/usr/bin/perl -w
use strict;
use Set::CrossProduct;

my $begin;
my $end;

if($ARGV[0] &amp;&amp; $ARGV[0] =~ /before/i){
    $begin = 0;
    $end = $ARGV[1];
}
elsif($ARGV[0] &amp;&amp; $ARGV[0] =~ /after/i){
    $end = 2400;
    $begin = $ARGV[1]; 
}
else{
    $begin = $ARGV[0];
    $end = $ARGV[1];
}

if(!defined($begin) || !defined($end)){
    print STDERR "Invalid Arguments\n";
    exit 1;
}

my @crontab = `crontab -l`;

foreach my $cronjob (@crontab){
    chomp $cronjob;

next if $cronjob =~ /^ *\#/ ||$cronjob =~ /^ *$/  ;

#print "in: $cronjob\n";

my ($min,$hour,$day_of_month,$month,$day_of_week, @cmd) = split(/ /, $cronjob);

my @mins = expandRange($min,0,59);
my @hours = expandRange($hour,0,23);

my $cp = Set::CrossProduct-&gt;new([\@hours,\@mins]);

my $combos = $cp-&gt;combinations();

foreach my $time ( map { $_-&gt;[0]*100 + $_-&gt;[1] } @$combos){
if($time &gt;= $begin &amp;&amp; $time &lt;= $end){
    print $cronjob,"\n";
    last; #don't print the job n times, just once
}
}


}

sub expandRange{

my ($in,$begin,$end) = @_;
#print "in: ($in)[$begin:$end]\n";
my @range;

my @vals = split(/,/,$in);
foreach my $val (@vals){
my $mult = 1;
if($val =~ /\/(.+)$/){
    $mult = $1;
    $val =~ s/\/(.+)//;
}

if($in =~ /\*/){
    @range = grep { $_ % $mult == 0 &amp;&amp; $_ &gt;= $begin &amp;&amp;  $_ &lt;= $end  } $begin..$end;
}
elsif($val =~ /[\-:]/){
    my ($first, $last) = split(/[\-:]/,$val);
    push(@range, grep {  $_ % $mult == 0 &amp;&amp; $_ &gt;= $begin &amp;&amp;  $_ &lt;= $end } $first..$last);
}
elsif($val &gt;= $begin &amp;&amp;  $val &lt;= $end) {
    push(@range, $val);
}
}

my %unique;
@unique{@range} = 1;

return sort keys %unique;


}