Objects that are given by names and contain data used by at least one, usually multiple applications are called environment variables. Put simply, an environment variable is nothing more than a variable that has a name and a value.
Values of environment variable could be the default editor that will be used, for example, the location of all files that can be executed in the system or local settings for the system. Beginners of Linux will find this a little difficult but the environment variable is an excellent way of sharing the configuration settings between several applications and processes.
In this tutorial, we will show you, how to use the Ubuntu crontab. In a few simple steps, we will explain, how to automate your system tasks on Ubuntu, using the crontab in Ubuntu. The cron software utility is a time-based job scheduler in Unix-like operating systems. Cron is driven by a crontab (cron table) file, a configuration file that specifies shell commands to run periodically on a given schedule. The crontab files are stored where the lists of jobs and other instructions to the cron daemon are kept. Users can have their own individual crontab files and often there is a system-wide crontab file (usually in /etc or a subdirectory of /etc) that only system administrators can edit.
