A shell script is in its simplest form, a recipe, where each line represents a command that is processed by the shell. For example, you may write a shell script to be used as a backup program, that collects a group of files, zips them, and then emails them to a specific email address.
Technically, a shell script is a program, with the advantage that you can quickly design and prototype your application without needing to use a low-level language like C.
Shell scripts help to automate repetitive tasks, and in addition, they can be called automatically from UNIX's cron daemon to that the shell script is executed on a schedule.
Paired with CygwinEdit
Cygwin ships with the bash shell, and with it you can call Cygwin binaries (usually in C:\cygwin\bin\), as well as MS Windows binaries (see here ).