comels/simple_shell

🐚 HOLBERTON PROJECT - SIMPLE SHELL 🐚

Code a simple shell for Holberton School.

PREREQUISITES

Only use the following 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)
fstat (man 2 fstat)
getcwd (man 3 getcwd)
getline (man 3 getline)
kill (man 2 kill)
lstat (man 2 lstat)
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 (man 2 stat)
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)

INSTALLING

Compile like this :

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

USAGE

Currently, when run, it looks like this :

simple_shell git:(main) ./hsh
#cisfun$ pwd
/home/vagrant/simple_shell
#cisfun$ cat _strlen.c
#include "simpleshell.h"

/**
 * _strlen - size of string
 * @s: string to find size
 * Return: string size
 */

int _strlen(char *s)
{
        int i = 0;

        while (s[i] != '\0')
        {
                ++i;
        }
        return (i);
}
#cisfun$ exit
simple_shell git:(main)

• This shell is a command-line interpreter that provides a command line user interface for Unix-like operating systems.

• It is both an interactive command language and a scripting language, and is used by the operating system to control the execution of the system using shell scripts.

Users type commands which get executed within the session.

EXAMPLE :

$pwd - to print working directory                              
$echo - to print to standard output                                             
$cat - to read a file's content                                                                                

FLOW CHART

CONTENTS

Below are the files in this repository and a description of the code they contain

main.c

Contains the main code of the shell where all the rest of the other functions are used to make the shell run.

Makes the Shell run continously and also listens for signals when a user presses ctrl + c

Returns 0 on success and 1 when something goes wrong as the shell runs

signal.c

Contains a function that listens for when a user presses ctrl + c and prevents the shell session from closing.

It prints a new line and clears the standard output instead of interrupting the running shell

Prototype : void ctrl_c(int signal);

func_read.c

Contains the function that gets the user input from standard input

Prototype : char *func_read(void);

Returns :

• The pointer to the string of input the user gave if successfull
• NULL if it fails

func_split.c

Contains the function that tokenises the user input and stores the resulting tokens in an array

Prototype : char **func_split(char *line);

Returns :

• The array of tokens if succesful
• NULL on failure

func_exec.c

Contains the function and it's where the actual linux commands are executed.

Prototype : int func_exec(char **args);

It also uses a few other functions.

Return :

• 1 on success
• 0 on failure

get_path.c

Contains the function that gets the full path of given command from the PATH variable

Prototype: char *get_path(char *getcmd);

Returns :

• A pointer to the full path of the command on success
• NULL on failure

get_env.c

Contains the function that finds the environment variable requested by user

Prototype : char *get_env(char *getcmd);

Returns :

• The value of the environment variable on success
• NULL on failure

split_env.c

Contains the function that tokenizes the PATH to return a list of folders

Prototype : char **split_env(char *path);

Returns :

• An array of directories on success
• NULL on failure

CUSTOM COMMANDS

Some custom commands for the shell

_printenv.c

Contains the function that pints all the environment variables

Prototype : void _printenv(void);

It is called by typing the command env in the shell

HELPER FUNCTIONS

These are some of the helper functions used across most of the core functions.

Most of these are also availabe in the standard library but we were supposed to write the functions ourselves

_strcat.c

Contains the function that concatonates two strings passed to it

Prototype : char *_strcat(char *dest, char *src);

Returns :

• A pointer to the new string

_strcmp.c

Contains the function that compares two strings

Prototype : int _strcmp(char *s1, char *s2);

Returns :

• 0 if equal
• negative value if less than
• positive if greater than

_strlen.c

Contains the function that finds the length of string

Prototype : int _strlen(char *s);

Returns :

• Length of the string passed on success

_strncmp.c

Contains the function that compares n bytes in str1 and str2

Prototype : int _strncmp(char *str1, char *str2, int n);

Returns :

• positif if str2 is less than str1
• negatif if str1 < str2,
• 0 is str1 is equal to str2

MAN FILE

man_1_simple_shell

This is the man file for the shell

Usage : man ./man_1_simple_shell

HEADER FILE

simpleshell.h

Contains all the function prototypes and header files used in this project.

Authors

Hiromi Varnier
Côme Le Sauter