TEMP-SH

A simple basic shell in linux kernel made in C language. This project has a list of built-in commands, as well as the others which bash features.

How To Run

Make sure you have GCC compiler installed. If you don't refer here.

Step 1. Download the source code to system in zip format or clone repo.

git clone https://github.com/pragyad3188/TEMP-SH.git

Step 2. On linux shell navigate to the folder

cd TEMP-SH

Step 3. compile the shell using command

gcc -o runshell  temp-sh.c utilities.c utilities.h linkedlist.c linkedlist.h

Step 4. run using command

./runshell

Tech Stack Used

• C language
• Use of pipe syscall present in <unistd.h>.
• Libraries such as <stdlib.h>for adding color.
• Some C libraries such as <sys/wait.h>,<sys/types.h> and <signal.h>.

Important Logic Used

Some basic utilities as thought in the project course have been kept intact like

• Support for background jobs
• Builtin necessary command for "cd" as it cannot be executed in a child
• Use of fork() and execv() to process bash commands
• Exiting the shell.
• Support for Signal Handling
• Killing of Processes

Some logic used for the Pipeline

• For a single stage pipeline, fork() two child processes from the parent process.They both share a pipe in common.
• For the first command make the stdout as one end of the pipe
• For the second command make the stdin as the other end of the previous pipe
• Wait for both the process to execute.

New Features

1. The support for a sinlge pipeline is successfully added using the pipe call privided by linux. Please Note that there must a space before and after "|" while giving the piped instruction. Usage Run the shell and type in following command

 cat abc.txt

We can see a number of texts displayed and some repeated. We can sort them and get the uniq ones only using pipeline by the following commmand.

    sort abc.txt | uniq

The output consists of sorted unique values.

2. Additional suppport for colours has been added to the shell.As of now red,blue,yellow,green,white are supported but many more can be added.
3. sh_history() method : Similar to the bash shell an history function is added which keeps track of the most recent 100 commands. They can be displayed in the following manner:- Usage : Once the shell is running type:-

   history
   

4. sh_help() method : A quick guide for anyone stuck with the shell.It shows a list of features available Usage : Once the shell is running type:-

   help
   

Working Demo

• The working of the pipelines along with the colour codes and the history and help command has been demonstarted by the pictures below.

Future Goals

• Addition of bash loop functionalities like for and while
• Addition and implementation of multiple pipelines