0x16. C - Simple shell

In this project we'll create a simple UNIX command interpreter in C programming language.

Table of Contents

• Introduction
  • What is Shell
  • What is it for
• Project Information
  • Tasks
  • General requirements
  • Allowed functions
• Documentation
  • Compilation
  • Testing
  • Files
  • Flowchart
• Extra Information
  • Resources
• Authors

Introduction

What is Shell

A shell is a command-line interpreter, it is the computer program that provides a user interface to access the services of the operating system. Depending on the type of interface they use, shells can be of various types, in this case, a shell program of the type sh (Bourne Shell) will be developed. Users typically interact with a shell using a terminal emulator that is used for entering data into and displaying or printing data from, a computer or a computing system.

What is it for

This consists of interpreting orders. It incorporates features such as process control, input/output redirection, law listing and reading, protection, communications, and a command language for writing batch programs or scripts. All Unix-type systems have at least one interpreter compatible with the Bourne shell. The Bourne shell program is found within the Unix file hierarchy at /bin/sh.

Project Information

Tasks

• Task 0. README, man, AUTHORS
• Task 1. Betty would be proud
• Task 2. Simple shell 0.1
• Task 3. Simple shell 0.2
• Task 4. Simple shell 0.3
• Task 5. Simple shell 0.4
• Task 6. Simple shell 1.0
• Task 7. What happens when you type ls -l in the shell

General 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
• 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
• This shell should not have any memory leaks
• Unless specified otherwise, your program must have the exact same output as sh (/bin/sh) as well as the exact same error output.

Allowed functions used

• execve (man 2 execve)
• exit (man 3 exit)
• _exit (man 2 _exit)
• fork (man 2 fork)
• free (man 3 free)
• getline (man 3 getline)
• isatty (man 3 isatty)
• malloc (man 3 malloc)
• perror(man 3 perror)
• signal (man 2 signal)
• stat (__ xstat) (man 2 stat)
• strtok (man 3 strtok)
• wait (man 2 wait)
• write (man 2 write)

Documentation

Compilation

Your shell will be compiled this way:

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

Testing

Your shell should work like this in interactive mode:

$ ./hsh
($) /bin/ls
hsh main.c shell.c
($)
($) exit
$

But also in non-interactive mode:

$ ./hsh
($) /bin/ls
hsh main.c shell.c
($)
($) exit
$

Files

##	File	Description
_builtin.c	Built-ins functions exit and print env
_fork_function.c	Create the fork function to execute the command types by the user
_get_token.c	Tokenize the strings
_get_path.c	Get the env to find the PATH
_getline_command.c	Print the $ and get what the user types
shell.h	Prototypes functions and headers
simple_shell.c	Our simple shell functions
_str_utils.c	Auxiliar strings functions
_values_path.c	Concatenate the path with the command
AUTHORS	Contributors in this repository
man_1_simpleShell	Manual page our of Simple Shell
README.md	Information about our repository

Flowchart

Authors

• Jocelyn Vega | Twitter | Github |
• Ricardo Arquímedes Castro | Twitter | Github |