0x15. C - Simple Shell

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Name

Shell - A simple shell

Description

This project recreates a simple command line shell that executes commands read from the standard input or from a file. It has been tested on Ubuntu 14.05.5 LTS.

• Can execute any commands from the environment path.

• Works on interactive and non-interactive mode.

• Commands must be on a single line.

• Arguments must be separated by whitespace.

• No quoting arguments and escaping whitespace.

• No piping or redirection.

• It doesn't handle aliases, comments or history.

• Built-in commands:

  • env (print a list of the current environment variables).

  • exit (exits the shell).

Example 1 | cat command

$ cat environ.c
#include "shell.h"

/**
 * print_env - a function that prints the environment.
 * Return: 0.
 */

int print_env(void)
{
	int i = 0;

	while (environ[i])
	{
		/* prints in form of "variable=value" */
		   write(1, environ[i], _strlen(environ[i]));
		   	    i++;
				write(1, "\n", 1);
				}
				return (0);
}

$

Example 2 | BUILT-IN COMMAND: exit

vagrant@simple_shell$ ./hsh
$ echo Quitting the simple shell with the exit command
Quitting the simple shell with the exit command
$ exit
vagrant@simple_shell$

How to Use

Clone repo

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

Change directory to simple_shell

cd simple_shell/

Compile all the .c files in /simple_shell

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

Project Requirements:

• Allowed editors: vi, vim, emacs
• All your files will be compiled on Ubuntu 14.04 LTS
• Your C programs and functions will be compiled with gcc 4.8.4 using the flags -Wall -Werror -Wextra and -pedantic
• All your files should end with a new line
• A README.md file, at the root of the folder of the project is mandatory
• Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl
• No more than 5 functions per file
• All your header files should be include guarded
• Use system calls only when you need to (why?)

List of allowed functions and system calls

• access (man 2 access)
• chdir (man 2 chdir)
• close (man 2 close)
• closedir (man 3 closedir)
• execve (man 2 execve)
• exit (man 3 exit)
• fork (man 2 fork)
• free (man 3 free)
• stat (__xstat) (man 2 stat)
• lstat (__lxstat) (man 2 lstat)
• fstat (__fxstat) (man 2 fstat)
• getcwd (man 3 getcwd)
• getline (man 3 getline)
• 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)
• strtok (man 3 strtok)
• wait (man 2 wait)
• waitpid (man 2 waitpid)
• wait3 (man 2 wait3)
• wait4 (man 2 wait4)
• write (man 2 write)
• _exit (man 2 _exit)
• isatty (man 3 isatty)
• fflush (man 3 fflush)

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File	Task
AUTHORS	the authors page
README.md	read me file
environ.c	prints the environment
error.c	handles errors
man_1_simple_shell	manual page
path.c	handles the PATH
shell.c	the main componenets of the shell
shell.h	the header file for the simple shell program
string.c	a series of functions to handle strings
tokenize.c	splits a string into tokens and count the number of tokens

Compilation

Files are compiled this way:

$ gcc -Wall -Werror -Wextra -pedantic *.c

Authors

Francesca Cantor || Twitter || email

Leine Valente || Twitter || email

Nicole Swanson || Twitter || email