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https://github.com/tjensen42/42-minishell
This project is about creating a simple shell. Like an own little bash. We learned a lot about processes, file descriptors and many other things about the shell itself.
https://github.com/tjensen42/42-minishell
42 42project bash minishell shell
Last synced: about 6 hours ago
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This project is about creating a simple shell. Like an own little bash. We learned a lot about processes, file descriptors and many other things about the shell itself.
- Host: GitHub
- URL: https://github.com/tjensen42/42-minishell
- Owner: tjensen42
- License: gpl-3.0
- Created: 2021-11-02T17:06:25.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2022-11-20T17:49:02.000Z (almost 2 years ago)
- Last Synced: 2023-03-05T19:09:07.180Z (over 1 year ago)
- Topics: 42, 42project, bash, minishell, shell
- Language: C
- Homepage:
- Size: 576 KB
- Stars: 16
- Watchers: 1
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# 42-minishell
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. ([tjensen42](https://github.com/tjensen42) && [hepple42](https://github.com/hepple42))
## 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
- ```&&``` and ```||``` with parenthesis for priorities
### 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 https://github.com/tjensen42/42-minishell.git minishell
```
```
cd minishell && make release
```
```
./minishell
```
## Dependencies
### Install readline with [brew](https://brew.sh/)
```
brew install readline
```
```
brew link --force readline
```
Add the path to the lib
Replace ~/.zshrc with ~/.bashrc if you use bash instead of zsh
```
echo 'export C_INCLUDE_PATH="/usr/local/opt/readline/include:$C_INCLUDE_PATH"' >> ~/.zshrc
```
```
echo 'export LIBRARY_PATH="/usr/local/opt/readline/lib:$LIBRARY_PATH"' >> ~/.zshrc
```
```
source ~/.zshrc
```
### 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 $HOME/.zshrc && brew update
```
Install Readline library:
```
brew install readline
```
```
brew link --force readline
```
```
echo 'export C_INCLUDE_PATH="$HOME/.brew/include:$C_INCLUDE_PATH"' >> ~/.zshrc
```
```
echo 'export LIBRARY_PATH="$HOME/.brew/lib:$LIBRARY_PATH"' >> ~/.zshrc
```
```
source ~/.zshrc
```
## Run tests
To check if your minishell build was succesful you can run a tester, which compares most of the features with your current Bash installation. The test compares the stdout and the exit-code directly and checks in case of an error if both print something in stderr.
```
make test
```
## Activate debug mode
Enter minishell and export the DEBUG env:
```
export DEBUG=printer
```
For all next commands you will execute in the minishell you will see the different processing steps from the lexer and parser with syntax highlighting.
## Change the command line prompt
1. Enter the SHELL
```
./minishell
```
2. Export the PS1 env (also works in Bash and other similar shells)
```
export PS1='enter your prompt wish...$ '
```
*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