tdameros / 42-minishell

As beautiful as a shell

Minishell Project

As beautiful as a shell

Minishell is a project from the 42 school curriculum that involves creating a basic shell similar to bash.

This project was realized in 2 months by :

• Vincent Fries (vfries)
• Tom Damerose (tdameros)

Get started

⚠️ Readline is required

make -j
./minishell

Subject

The subject only allows the following functions as well as the readline library. Everything else must be recoded from scratch.

External 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

Not use more than one global variable. Think about it. You will have to explain its purpose.

Functionalities

Operators

Operator	Example command
Input redirection: <	grep 'shell' < Makefile
Output redirection: >	cat Makefile > test.txt
Append output redirection: >>	cat Makefile >> test.txt
Here documents: <<	cat << EOF
Pipes: |	ls | grep 'c'
And: &&	apt update && apt upgrade
Or: ||	something || echo Hello World
Parenthesis: ( & )	(ls || echo Hello World) && echo minishell

Interactive Mode

Interactive Minishell interprets unclosed quotes and unfinished commands.

Minishell can be executed with the -c option to run a command without entering interactive mode.

Shortcut	Feature
ctrl-C	displays a new prompt on a new line
ctrl-D	exits the shell
ctrl-\	does nothing

Builtins

Builtin	Implementation
echo	with option -n
cd	with only a relative or absolute path
pwd	with no options
export	with no options
unset	with no options
env	with no options or arguments
exit	with no options
alias	with no options
unalias	with no options

Expansions

Minishell alias implementation is not recursive and does not allow to interpret operators like bash.

1. Tildes (~, ~+, ~-)
2. Environment variables (echo $PWD)
3. Word splitting
4. Wildcards (only * in every directory: echo /*/*)
5. Quotes removal ("l"'s')

Minishellrc

At startup the .minishellrc file in the HOME path is executed.

Example :

alias g='git'
alias gcl='git clone'
alias gco='git checkout'
alias gl='git pull'
alias gb='git branch'
alias gp='git push'
alias gst='git status'

alias l='ls -lah --color=auto'
alias la='ls -lAh --color=auto'
alias ll='ls -lh --color=auto'
alias ls='ls -G --color=auto'
alias lsa='ls -lah --color=auto'

alias md='mkdir -p'
alias rd='rmdir'

alias ..='cd ..'
alias ../..='cd ../..'
alias ../../..='cd ../../..'
alias ../../../..='cd ../../../..'