selma-belhadj/simple_shell

Unix shell built to mimic sh

Simple Shell

In this project, we coded from scatch a simple Unix shell. A shell is an interactive command-line interpreter. We created a shell that would utilize the command line interface (CLI). It allows users to type in a defined set of commands (e.g. "rm" to remove files, "cat" to combine word documents, etc) and have the operating system run the appropriate function. It is slightly different from a graphical user interface (GUI). A user can create/write/read/open/remove folders, print things to the terminal, change directories, print where you are in the system, etc.

Synopsis

This repository holds all the code necessary for our custom simple shell to run. Our shell currently handles the executions of executables found in the environmental variable PATH, with or without their full paths. Sample commands that our shell supports include ls (/bin/ls), pwd, echo, which, whereis, etc. We've also created the following builtins.

Builtins

• exit exits shell (Usage: exit [status])
• env prints environmental variables (Usage: env)
• setenv creates or modifies an environmental variable (Usage: setenv name value)
• unsetenv removes an envrionmental variable (Usage: unsetenv name value)
• cd changes directories (Usage: cd [-][~][path])

Functions and system calls used

read, signal, malloc, free, getcwd, chdir, access, execve, wait, write, exit

Description of what each file shows:

man_3_shell ------------------------ custom manpage for our simple shell
main.c ----------------------------- holds entrance into program
shell.h ---------------------------- holds prototypes of functions spread across all files

Helper files

prompt.c --------------------------- handles outline of shell's reprompting and executing
non_interactive.c ------------------ handles output when shell is called outside of shell
_realloc.c ------------------------- helper function handles reallocation
_strcat.c -------------------------- concatenates two strings
_strcmp.c -------------------------- compares if two strings match
_strcpy.c -------------------------- copies a string
_strdup.c -------------------------- duplicates a string
_str_tok.c -------------------------- (custom) tokenizes user's command input and returns array
c_str_tok.c ------------------------- tokenizes PATH to include ":" as Null, checks current dir
get_line.c ------------------------- (custom) reads user's typed input into buffer
_which.c --------------------------- appends command to PATHs, fleshes paths out, returns match
_cd.c ------------------------------ changes directories
linked_lists.c --------------------- adds and deletes nodes; prints and frees linked list
get_env.c -------------------------- finds and returns copy of environmental variable
env_linked_list.c ------------------ prints and creates linked list of envrionmental variables
set_unset_env.c -------------------- finds environment variable index node, sets and unsets
free_double_ptr -------------------- frees double pointers (user's command, arrays)
_execve.c -------------------------- executes and frees command, then exits program
__exit.c --------------------------- handles if user types exit or exit(value)
int_to_string.c -------------------- converts int to string to write error messages
print_error.c ---------------------- prints special error messages for certain fails

Environment

• Language: C
• OS: Ubuntu 14.04 LTS
• Compiler: gcc 4.8.4
• Style guidelines: Betty style

How To Install & Compile

$ git clone [email protected]:selma-belhadj/simple_shell.git
$ cd simple_shell
$ gcc -Wall -Werror -Wextra -pedantic -std=gnu89 *.c -o hsh
$ ./hsh

Authors

👤 Selma Belhadj

• GitHub: @selma-belhadj
• Twitter: @Bel_Selma16
• LinkedIn: @selma-belhadj

👤 Kanu Mike Chibundu

• GitHub: @Ginohmk
• Twitter: @michotall95
• LinkedIn: @kanumike

🤝 Contributing

Contributions, issues, and feature requests are welcome!

Feel free to check the issues page.

Show your support

Give a ⭐️ if you like this project!

Acknowledgments

• Hat tip to anyone whose code was used
• Inspiration
• etc

📝 License

This project is MIT licensed.