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

  • General requirements
  • Allowed functions

• Documentation

  • Download
  • Compilation
  • Testing
  • Files
  • Show flowchart

• Extra Information

  • Resources

• Authors

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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

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

• 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)

Documentation

Download

You can clone this repository this way: git clone https://github.com/nathsotomayor/simple_shell.git

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
$

Also in non-interactive mode:

$ echo "/bin/ls" | ./hsh
hsh main.c shell.c test_ls_2
$
$ cat test_ls_2
/bin/ls
/bin/ls
$
$ cat test_ls_2 | ./hsh
hsh main.c shell.c test_ls_2
hsh main.c shell.c test_ls_2
$

Files

##	File	Description
1	README.md	Readme
2	man_1_simple_shell	Man page Simple Shell based in sh(1) - Linux man page
3	main.c	Entry point
4	holberton.h	Header file
5	interactive.c	It runs when it receives input through the non-interactive modes echo and cat, in addition to real-time execution.
6	non_interact.c	Error message when you receive parameters using the argc and argv arguments.
7	create_process.c	This function validates the existence of a file locally, and $PATH, if the file exists, creates a child process that validates all its error states. Using the stat() , fork() , execve() and waitpid() functions
8	validate_file.c	This function validates if a file is found in the paths of the system PATH by means of the stat system call.
9	_getenv.c	This function returns a specified environment variable.
10	_exit.c	This function return a value especific of exit.
11	printf_env.c	This function emulates the operation of the env function, printing the environment variables.
12	str_function.c	Auxiliary functions for handling character strings: strlen() , _strcat() , _strcpy() and _strdup() .
13	strcmp_function.c	Auxiliary functions for character string comparison: _strcmp() and _strncmp() .
14	_calloc.c	This function emulates the operation of the calloc() function. Allocate and zero-initialize array

Flowchar

Flowchar

Extra information

Resources

Read or watch:

• The Magic Behind the Command ls -l
• Thompson shell
• Ken Thompson

man or help:

• sh (Run sh as well)

Authors

• Nathaly Sotomayor Ampudia
• Juan Sebastián Llano
• Camilo Moncada

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Made with 💛 in Holberton School Colombia (Cali)