Scuffed Shell

Purpose

scuffed_shell is a simple Unix shell that supports:

• running simple commands
• redirecting stdin, stdout, and stderr

Documentation for the shell can be found here.

Installing

Prerequisites

This program assumes the DC libraries are installed. If not, installation instructions can be found here.

Note: If you encounter any error claiming ndbm.h not found try the following commands

sudo apt-get install apt-file
sudo apt-file update
sudo apt-file search ndbm.h
sudo apt install libgdbm-compat-dev
sudo apt install libgdbm-dev

Building

cmake -S . -B build cmake --build build

The compiler can be specified by passing one of the following to cmake:

• -DCMAKE_C_COMPILER="gcc" -DCMAKE_CXX_COMPILER="g++"
• -DCMAKE_C_COMPILER="clang" -DCMAKE_CXX_COMPILER="clang++"

Running

./ScuffedShell

Environment Variables

The following environment variables alter the behaviour of scuffed_shell:

Variable	Purpose
PATH	The directories to search for commands
PS1	The prompt to display, if not set, defaults to ‘$.’

Features

• scuffed_shell only supports executing simple commands with optional I/O redirection.
• The PATH environment variable is searched for each command.
• After a command completes, the exit status is displayed.

Built-in Commands

scuffed_shell supports the following built-in commands:

Command	Purpose
cd	Change working directory
exit	Exit the shell

Limitations

• A program name has a space it cannot be run
• Tab completion is not implemented
• Command history is not implemented

The following command types are not supported:

• Pipelines (|)
• Lists (;, &, &,&, ||)
• Compound (if, case, until, while, for, ())
• Functions

Examples

Startup

Cat command

Multiple commands

Exit