/**
  * Install a cron job that runs at a custom time (other than the .hourly/
  * .daily/.weekly/.monthly. A file in the same format as /etc/crontab is
  * created in /etc/cron.d with permissions 644.
  * 
  * $fileName should not have any extension and is the name of the file that
  *           wil be created in $cronPath.
  *
  * $time is a string that represents the customary cron time format:
  *   minute   hour   day   month   dayofweek
  *
  *   minute    - any integer from 0 to 59
  *   hour      - any integer from 0 to 23
  *   day       - any integer from 1 to 31 (must be a valid day if a month is
  *               specified)
  *   month     - any integer from 1 to 12 (or the short name of the month such
  *               as jan or feb)
  *   dayofweek - any integer from 0 to 7, where 0 or 7 represents Sunday (or
  *               the short name of the week such as sun or mon)
  *
  *   Example: run the command at 7 am every day
  *            0 7 * * *
  *
  * $sfTaskCall is the symfony command line that the script should execute.
  *
  * @param <type> $cronPath   Path to the cron directory (must be /etc/cron.d)
  * @param <type> $fileName   Name of the file to be created in $cronPath
  * @param <type> $time       Cron time format (see above)
  * @param <type> $sfTaskCall The command to call
  */
 public static function custom($fileName, $time, $sfTaskCall, $cronPath = '/etc/cron.d')
 {
     $DS = DIRECTORY_SEPARATOR;
     $fullPath = $cronPath . $DS . $fileName;
     $command = $time . ' root php ' . sfConfig::get('sf_root_dir') . $DS . $sfTaskCall . PHP_EOL;
     uFs::file_put_contents($fullPath, $command);
     uFs::chmod($fullPath, 0644, true);
 }