Simple Shell

About

Modeled after the first Unix shell by Ken Thompson, the sharpie shell (hereinafter referred to as sharpiesh) handles commands located in the $PATH and supports a number of additional, built-in features listed below.

Built-In Commands

Built-in	Use
exit	exits the shell
env	prints the current environment

Additional Features

• Handles file as piped input
• Handles multiple commands seperated by ';' delimeter
• Contains no memory leaks

Getting Started

A starter's guide to setting up sharpiesh.

1. Install

To download a copy of the source code locally, please run the following command in your terminal:

$ git clone https://github.com/wescottsharples/simple_shell.git

2. Compile

After downloading the source code, you can use the following command to compile a working version of the shell:

gcc -Wall -Werror -Wextra -pedantic *.c -o 'sharpiesh'

3. Use

sharpiesh should now be ready to use. To start the shell in interactive mode, please use the following command:

./sharpiesh

You should now see a $, which means sharpiesh is awaiting input.

Executing Commands

There are many commands you can execute from within sharpiesh. A comprehensive list of available Unix commands can be found here. Below are some examples of things you can try.

---

ls -l

ls lists the contents of your current directory. The -l flag specifies the listing should be in long format.

$ ls -l
total 28
-rwxrwxr-x 1 vagrant vagrant 18533 Nov 18 21:50 a.out
-rw-rw-r-- 1 vagrant vagrant   746 Nov 18 21:50 shell.c
drwxrwxr-x 2 vagrant vagrant  4096 Nov 18 21:50 simple_shell
-rw-rw-r-- 1 vagrant vagrant     0 Nov 18 21:49 words.txt

---

echo anything

echo displays a line of text. It takes a string of characters to be displayed as an argument.

$ echo anything
anything

---

touch file.txt

touch creates a new file in the current directory. It takes a file name, such as file.txt as an argument.

$ touch file.txt
$ ls
a.out  file.txt  shell.c  simple_shell	stuff.txt

---

rm file.txt

rm deletes a file. It takes a file name, such as file.txt as an argument.

$ rm file.txt
$ ls
a.out  shell.c  simple_shell	stuff.txt

---

exit

exit exits the shell.

$ exit
vagrant@vagrant-ubuntu-trusty-64:~/simple_shell$

---

man

To view documentation on each command, you can use man followed by the command you would like to know more about. For example, man ls will display information about the command ls.

Interactive vs. Non-Interactive Mode

You can use the shell in both interactive and non-interactive mode. The examples above are done in interactive mode. You can tell because the shell runs continuously, awaiting and executing commands, until you explicitly exit.

Non-interactive mode, however, is when you indirectly feed commands into the executable hsh file from outside the shell. For example, we can list files by indirectly piping ls into hsh using echo:

$ echo "ls" | ./hsh
a.out  shell.c  simple_shell	stuff.txt

Environment Information

This shell was built and tested in the following environment by Samie Azad and Wescott Sharples as a project for Holberton School.

Feature	Version
Language	C
Operating System	Ubuntu 14.04 LTS
Compiler	gcc 4.8.4
Style Guidelines	Betty

To test sharpiesh, or any other Unix shell, you can use this test suite developed by our classmates for this project.