Shell Programming and Scripting

gawk -v FS="," 'BEGIN { REF=systime() - (30 * 24 * 60 * 60); }
{
        # Split DD/MM/YYYY HH:MM:SS into DD MM YYYY HH MM SS
        split($4, a, " ");
        split(a[1], da, "/");
        split(a[2], ta, ":");
        # add seconds if missing
        if(!ta[3]) ta[3]="00";
        # paste into YYYY MM DD HH MM SS and make timestamp
        t=mktime(da[3] " " da[2] " " da[1] " " ta[1] " " ta[2] " " ta[3]);
# Only print when t is newer than 30 days ago
}       (t>REF)' < input > output

#!/usr/bin/perl

use Time::Local;
use Time::localtime;

$today = time();
$range = 30*24*60*60;

while (<ARGV>) {
    @f = split /,/, $_;
    @dt = split /[ :\/]/, $f[3];

    $dy = $dt[0] ? $dt[0] : 0;
    $mo = $dt[1] ? $dt[1] - 1 : 0;
    $yr = $dt[2] ? $dt[2] - 1900 : 0;
    $hr = $dt[3] ? $dt[3] : 0;
    $mi = $dt[4] ? $dt[4] : 0;
    $se = $dt[5] ? $dt[5] : 0;

    $sfe = timelocal($se,$mi,$hr,$dy,$mo,$yr);
    print if ($today - $sfe < $range);
}

perl_script input_file