minishell - 42 Heilbronn (February 2022)

The objective of this project is to create a simple shell, like an own little bash.
It is the first group project in the 42 core curriculum.

Project specifications

For the project we were allowed to use GNU's readline library which handles the terminal interaction (history & input reading). For everything else the subject allows only to use a few low-level functions and a few POSIX system calls.

Allowed functions: readline, rl_clear_history, rl_on_new_line,rl_replace_line, rl_redisplay, add_history, printf, malloc, free, write, access, open, read,close, fork, wait, waitpid, wait3, wait4, signal, sigaction, sigemptyset, sigaddset, kill, exit, getcwd, chdir, stat, lstat, fstat, unlink, execve, dup, dup2, pipe, opendir, readdir, closedir, strerror, perror, isatty, ttyname, ttyslot, ioctl, getenv, tcsetattr, tcgetattr, tgetent, tgetflag, tgetnum, tgetstr, tgoto, tputs

Features

Basics:

History of previous entered commands
Search and launch the right executable (based on the PATH variable, using a relative or an absolute path)
Environment variables ($ followed by a sequence of characters) expand to their values
Wildcards * in the current working directory
ctrl-C, ctrl-D and ctrl-\ behave like in bash
’ (single quotes - prevent from interpreting meta-characters in quoted sequence)
" (double quotes - prevent from interpreting meta-characters in quoted sequence except for $)
$? expands to the last exit status
| connect cmds or groups with pipes; output of a cmd is connected to the input of the next cmd via a pipe

Builtins:

echo with option -n
cd (relative or absolute path, - for OLDPWD, without arg for HOME)
pwd without options
export without options
unset without options
env without options
exit [exit_status] without options

Redirections:

[n] (optional) specifies the file descriptor, if not specified it is stdout/stdin

[n]< file Redirecting Input
[n]<< limiter Here Documents
[n]> file Redirecting Output
[n]>> file Appending Redirected Output

How to use

The current version of minishell is developed and tested on macOS, but it should work on all UNIX/LINUX based systems as well.

Requirements:

GCC / CLANG Compiler
GNU Make
GNU Readline library

git clone

make all

./minishell

Dependencies

Install readline with brew

brew install readline

brew link --force readline

Add the path to the lib

Install readline on 42 Macs

Install Brew, only if it is not already installed:

rm -rf $HOME/.brew && git clone --depth=1 https://github.com/Homebrew/brew $HOME/.brew && echo 'export PATH=$HOME/.brew/bin:$PATH' >> $HOME/.zshrc && source $HOME/.zshrc && brew update

Install Readline library:

brew install readline

*All 42 projects must be written in C (later C++) in accordance to the 42 School Norm.

Sample restrictions:

All variables have to be declared and aligned at the top of each function

Each function can not have more then 25 lines

Projects should be created with allowed std functions otherwise it is cheating

xhazm / minishell