minishell

This group project is about creating a simple shell.
Just like bash, but a little bit smaller.
The goal was to learn how the system handles processes, file descriptors and signals.

I also learned how to lexically analyze plain input text into seperate word-tokens and recursively parse those tokens into an abstract syntax tree. Abstract syntax trees are data structures widely used in compilers to represent the structure of program code. I used it to represent the structure of any given shell input command.

minishell has the following builtins to offer:
echo: display a line of text (e.g. echo hello world)
env: prints the environment
exit : causes process termination
export: set the export attribute for variables (e.g. export key=value)
pwd : print working directory
unset : unset values and attributes of variables

The shell can also...

• browse through command history with up and down keys
• search and launch the right executable based on the PATH variable
• handle single quotes
• handle double quotes
• redirect input command < input
• redirect output command > output
• handle heredocs command << delimeter
• redirect and append output command >> output
• pipe output command_1 | command_2
• expand environment variables echo $HOME
• expand last exit status echo $?
• handle ctrl-C, ctrl-D and ctrl-\ like in bash

Installation

$ make

Running the app

$ ./minishell