User friendly task scheduler with crontab

Project motivation

As a team we aim to simplify the use of command-line commands that aim to schedule tasks for the user, by building a more user friendly interface for a UNIX 'task scheduler'.

Description:

This project aims to make task-scheduling in Unix OS systems much simpler and user friendly. For this project we are using 'cron' "a Unix, solaris, Linux utility that allows tasks to be automatically run in the background at regular intervals by the cron daemon."

For the management of the task & their respective scheduling, we are using 'crontab' (in short for: "CRON TABle"), which is a file that contains the schedule of cron entries to be run and at specified times by the user.

Cron job (or cron schedule) is a specific set of execution instructions specifying day, time and command to execute. crontab can have multiple execution statements within itself.

How it works?

1. Run the script by typing the following in to the console/terminal: ./crontab-ui.sh
2. You are presented with a menu with numbered options to manage your tasks.
3. Select an option by typing in the console the corresponding number to that command, ie: 1. Display all jobs will display all current active scheduled jobs once you press 1

Available commands:

command	description
1	Display crontab jobs
2	Insert a job
3	Edit a job
4	Remove a job
5	Remove all jobs
9	Exit

Usage Examples (In-depth):

Here we will show you how to use or script.

First and foremost, you must run the script by typing the following in to the console/terminal: ./<filename.sh>

You are presented with a menu with numbered options to manage your tasks.

Select an option by typing in the console the corresponding number to that command, ie: 1. Display all jobs will display all current active scheduled jobs once you press 1

Display crontab jobs [1]:

If you have typed 1 then you will obtain an output (list-like) of all of the current active crontab jobs.

Inserting a job [2]:

If you have typed 2 then you will be presented with a series of questions to configure your to-be scheduled task: whether you want a custom schedule or use a preset schedule command, when you want your task to run & what will the task do.

Using Custom Schedule Commands

Using Pre-set schedule commands

Editing a job [3]:

If you have typed 3, you will be presented with a prompt input to search by task commands. If the searched task command exists, then you will be asked to change the scheduled task to whatever you want through a similar set of 'config' questions like in command 2 Inserting a job.

Remove a job [4]:

If you have typed 4, you will be presented with a prompt input to search by task commands. If the searched task command exists, that task will be removed from the your scheduled tasks.

Remove all job [5]:

If you have typed 5, all of the scheduled tasks will be removed.

Exit task scheduler [9]:

If you have typed 9, you will exit the task scheduler user interface.

Further technical code doc.

For this project we have used a variety of different commands to fulfill our task scheduler. We listed & explained in detail the commands below, with examples of how we used them from our project code.

• grep- stands for: g/re/p (globally search a regular expression and print). This commands has the same effect: doing a global search with the regular expression and printing all matching lines.

• sed - stands for stream editorsed. As a command it receives input text as a “stream” and edits the stream according to your instructions (filter). By and large, people use sed as a command line version of find and replace.

• cat - The cat (short for “concatenate“) command is one of the most frequently used command in Linux/Unix like operating systems. cat command allows us to create single or multiple files, view contain of file, concatenate files and redirect output in terminal or files.

• IFS - The IFS is a special shell variable. You can change the value of IFS as per your requirments. The Internal Field Separator (IFS) that is used for word splitting after expansion and to split lines into words with the read builtin command.

• read - Read is a bash builtin command that reads the contents of a line into a variable. It allows for word splitting that is tied to the special shell variable IFS. It is primarily used for catching user input but can be used to implement functions taking input from standard input.

• tail - ‘tail’ command reads last 10 lines of the file. If you want to read more or less than 10 lines from the ending of the file then you have to use ‘-n’ option with ‘tail’ command.

Requirements:

No requirements...lol...jk. Only works in Linux/Ubuntu/Unix OS ;) Have fun scheduling!