Minishell

A simple command line interpreter written in C, taking the Bourne-Again Shell (bash) as inspiration.

Description

Minishell is a small-scale shell that allows you to execute commands, manage files, and navigate the file system. It's one of our biggest projects in 42 school that involves writing a shell with basic features like command execution, pipelines, I/O redirection, and built-in commands.

Features

• Prompt Display: Shows a prompt when waiting for a new command.
• Command History: Keeps a history of executed commands.
• Command Execution: Searches and runs executables based on the PATH environment variable or using a relative/absolute path.
• Hashing: Uses a simple hashtable to remember utility locations. Building a path for commands is necessary only once. If PATH changes, the hashtable gets automatically cleared.
• Signal Handling: Properly handles Ctrl-C and Ctrl-\ similar to bash.
  • Ctrl-C: In parent process: displays a new prompt on a new line. Default SIGINT in children.
  • Ctrl-\: Ignored in parent process. Default SIGQUIT in children.
  • Ctrl-D (this is actually not a signal, but EOF): can be used to delimit a heredoc or exit the shell.
• Quotes:
  • Single quotes ': Prevent the shell from interpreting metacharacters in the quoted sequence.
  • Double quotes ": Prevent interpretation of metacharacters except for $ (dollar sign).
• Variable expansion:
  • Handles the expansion of environment variables using $. For any NAME=value present in env, $NAME in the command line gets replaced with value. Word splitting is performed on value (except for redirections).
• Redirections:
  • <: Input redirection.
  • >: Output redirection.
  • << (heredoc): Reads input until a delimiter is found.
  • >>: Output redirection in append mode.
• Pipes: Supports the | character to connect commands.
• Exit Status: Supports $? to get the exit status of the last executed command.

Built-in Commands

• echo with -n option: prints its arguments. -n removes the trailing newline.
• cd with a relative or absolute path: changes directory.
• pwd without options: prints the name of the current/working directory.
• export with arguments: sets the value of a new or existing environment variable. Local assignment is also supported to an extent.
• unset with arguments: removes an existing variable from the environment list.
• env without options or arguments: displays the environment variable list.
• hash without options or arguments: displays all key/value pairs currently stored in the hashtable.
• exit with one argument: exits the shell with argument exit status.

Installation and use

Clone the repository, compile the source code & run the executable:

git clone https://github.com/rybarska/minishell_bonefire.git
cd minishell_bonefire
make
./minishell

Be aware that it will probably not run on your mac for our use of x86-64 inline Assembly.