Simple Shell Project

A simple Unix command line interpreter

---

Table of contents

• What is the shell?
• About this project
• Essential Functionalities of the Simple Shell
• File description
• List of allowed functions and system calls for this project
• USAGE
• Example of Usage
• Bugs
• TEAM

---

What is the shell?

The shell is a program that takes commands from the keyboard via the terminal, and gives them to the operating system to perform.
To better understand how the shell actually works, you can read our [Article].

About this project

This project is a simple version of the linux shell made for [Holberton School] taking part of the "Low-level programming & Algorithm - Linux and Unix system programming" projects.
It is created using the C programming Language and it can do many functionalities that a real shell does.

Essential Functionalities of the Simple Shell:

Displays a prompt "#cisfun$ " and waits for user input.
Runs all commands of type "executable program" (ls and /bin/ls).
Runs the following build_in commands: exit, env, setenv and unsetenv.
Handles commands with arguments.
Handles the PATH global variable.
Handles The EOF (End Of File) condition.
Handles the Ctrl + C signal -> It doesn't exit the shell

Files description

• AUTHORS -> List of contributors to this repository
• man_1_simple_shell -> Manual page for the simple_shell
• shell.h -> Header file
• shell.c -> main function
  • sig_handler -> handles the Ctrl + C signal
  • _EOF -> handles the End Of File condition
• string.c
  • _putchar -> prints a character
  • _puts -> prints a string
  • _strlen -> gives the length of a string
  • _strdup -> copies a string in a newly allocated memory
  • concat_all -> concatenates 3 strings in a newly allocated memory
• line_exec.c
  • splitstring -> splits a string into an array of words
  • execute -> executes a command using execve
  • realloc -> reallocates a memory block
  • freearv -> frees a 2 dimensional array
• linkpath.c
  • _getenv -> returns the value of a global variable
  • add_node_end -> adds a node in a singly linked list
  • linkpath -> creates a singly linked list for PATH directories
  • _which -> finds the pathname of a command
  • free_list -> frees the linked list of PATH value
• checkbuild.c
  • checkbuild -> checks if a command is a build-in command
• buildin.c
  • exitt -> handles the exit buildin command
  • _atoi -> converts a string into an integer
  • env -> prints the current environment
  • _setenv -> Initialize a new global variable, or modify an existing one
  • _unsetenv -> remove a global variable

---

List of allowed functions and system calls for this project

• access (man 2 access)
• chdir (man 2 chdir)
• close (man 2 close)
• closedir (man 3 closedir)
• execve (man 2 execve)
• exit (man 3 exit)
• _exit (man 2 _exit)
• fflush (man 3 fflush)
• fork (man 2 fork)
• free (man 3 free)
• getcwd (man 3 getcwd)
• getline (man 3 getline)
• isatty (man 3 isatty)
• kill (man 2 kill)
• malloc (man 3 malloc)
• open (man 2 open)
• opendir (man 3 opendir)
• perror (man 3 perror)
• read (man 2 read)
• readdir (man 3 readdir)
• signal (man 2 signal)
• stat (__xstat) (man 2 stat)
• lstat (__lxstat) (man 2 lstat)
• fstat (__fxstat) (man 2 fstat)
• strtok (man 3 strtok)
• wait (man 2 wait)
• waitpid (man 2 waitpid)
• wait3 (man 2 wait3)
• wait4 (man 2 wait4)
• write (man 2 write)

---

USAGE

You can try our shell by following these steps:

Step 1: Clone our repository using this command, (you need to have git installed on your machine first)

git clone https://github.com/abdelhamedatef2/simple_shell

Step 2: Change directory to simple_shell:

cd simple_shell

Step 3: Compile the C files in this way:

gcc -Wall -Werror -Wextra -pedantic *.c -o hsh

Step 4: Run the shell

./hsh

Exiting the shell When you want to exit the shell, you can use one of the following methods:

1: Type the command "exit"

exit

2: Press on Ctrl + D

Example of Usage

ubunto@ubuntu:~/Bureau/simple_shell$ gcc -Wall -Wextra -Werror -pedantic *.c -o hsh
ubunto@ubuntu:~/Bureau/simple_shell$ ./hsh
#cisfun$ echo Hello, This is an example
Hello, This is an example
#cisfun$ ls
README.md  checkbuild.c  line_exec.c  shell.c  string.c
buildin.c  hsh		 linkpath.c   shell.h
#cisfun$ ^C
#cisfun$ ls -l
total 52
-rw-r--r-- 1 ubunto ubunto  3067 Nov 26 04:22 README.md
-rw-r--r-- 1 ubunto ubunto  2183 Nov 24 16:17 buildin.c
-rw-r--r-- 1 ubunto ubunto   574 Nov 24 15:59 checkbuild.c
-rwxr-xr-x 1 ubunto ubunto 18144 Nov 26 04:22 hsh
-rw-r--r-- 1 ubunto ubunto  2091 Nov 24 14:49 line_exec.c
-rw-r--r-- 1 ubunto ubunto  1926 Nov 24 14:30 linkpath.c
-rw-r--r-- 1 ubunto ubunto   951 Nov 24 16:09 shell.c
-rw-r--r-- 1 ubunto ubunto  1351 Nov 24 15:58 shell.h
-rw-r--r-- 1 ubunto ubunto  1727 Nov 24 14:30 string.c
#cisfun$ exit
ubunto@ubuntu:~/Bureau/simple_shell$

Bugs

No known Bugs.