smallsh - A Simple Unix Shell Implementation

smallsh is a lightweight Unix shell implementation written in C. It provides basic shell functionality with support for built-in commands, input/output redirection, background processes, and signal handling.

Features

• Command execution with support for built-in commands (cd, exit)
• Input/output redirection (<, >, >>)
• Background process execution (&)
• Environment variable expansion ($VAR, ${VAR})
• Special parameter expansion ($$, $?, $!)
• Signal handling (SIGINT, SIGTSTP)
• Comment support (#)

Built-in Commands

• cd [directory]: Change the current working directory
• exit [status]: Exit the shell with an optional status code

Usage

Compile the program:

gcc -o smallsh smallsh.c

Run the shell:

./smallsh

Implementation Details

• Uses POSIX-compliant system calls and functions
• Implements a custom word splitting function
• Handles parameter expansion with a simple string builder
• Manages background processes and reports their status

Limitations

• Maximum of 512 words per command
• Does not support advanced features like piping or command substitution