Ghost Shell- A simple shell

GSH

Ghost Shell also known as the shell is a simple command line prompt that takes the most basics of commands that are present in the bash shell and runs them. This shell was built as a project for Holberton School.

the shell works like the bash and other basic shells.

The shell works by being compiled using GCC 4.8.5 compiler or later versions. The shell can compile using gcc 4.8.4 -Wall -Werror -Wextra -pedantic *.c -o shell.

Example of how to launch the shell after compiling:

./shell

• Output: prompt to terminal: $

Syntax

The shell works by using commands given by the user input. The shell commands take in the following syntax: command name {arguments}. The shell executes a command after it is written by user using the command followed by the arguments.

cat holberton.h The above example takes in a command by the user followed with the arguments. In this case the command is cat (to view file without opening file) followed by argument the file name in this case holberton.h.

For more information on cat, you can use the man command which will show a manual of the given command or any command you wish to know more information on. It contains system calls, libraries and other important files.

The shell also contains two builtins which are commands that are within the shell itself. The two builtins are exit and env. You can also use help command to know which builtins are provided by the shell. The help command works similarly to the manual where it provides further detail or information on given builtin.

Compilation

All files will be compiled with the following: $ gcc -Wall -Werror -Wextra -pedantic *.c

List of useful commands

• cat - prints and concatenates files to the standard output
• cp -copies a file into another file
• grep - helps to search for a file in a specific pattern
• less - will let you go backward and forward in the files
• ls - will list all files and directories in current working directory
• mv - helps to move one file into another file
• pwd - given you the current working directory

Builtins

There are two builtins programmed into the shell. Below is a description and use for each builtin.

• env - The env command is a command that tells the shell program to display all of the environment variables with their values. It is a way to access those values through the shell.

• exit - If you wish to exit out of the shell the user can use the builtin exit.

Exiting commands and the shell

To exit out of a command or process the user can use ctrl c. Control c stops a process and causes it to abort. The user can also utilize the command ctrl D which will just exit. When the command ctrl D is used an exit status of 0 is given. Using exit, you can input its exit status or it is defaulted to the status of the last command executed.

Files

• README.md : Current file, contains information about this project
• holberton.h : Header file, contains all prototypes for funcitons used, as well as libriaries
• hsh.c: Main file that uses most functions and executes them within this file
• ghostinshell.png: Image in readme file
• _getenv.c : Contains the code for _printf
• _getline.c: File for getting prompt and user input
• which.c: File containing the specific functions for conversion specifiers
• builtin_execute.c: Executing the builtins
• builtins.c: File containing the two builtins
• child.c: File that forks and creates parent child processee
• free.c: File with free malloc functions
• prompt.c: File with actual prompt line $
• tokenizer.c: File that creates function to tokenize an array of strings
• utility_functions.c: helper functions

Comments

Authors

• Wendy Segura - https://github.com/wendysegura
• Carrie Ybay - https://github.com/hicarrie