A minimal shell implementation in C that demonstrates core Unix process management and command execution fundamentals. This project separates concerns into discrete modules for command parsing, built-in operations, and external process spawning.
The shell is structured around three primary execution paths:
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built_in.c: Handles built-in commands (cd, pwd, exit, help) without process forking. These operations execute within the parent shell context.
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pid.c: Manages external command execution through fork/execvp. Returns exit status to enable proper command chaining behavior. Error handling differentiates between fork failures and command not found conditions.
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execute_command.c: Route dispatcher that checks for built-in commands first, then delegates to pid_function for external commands. Centralizes control flow logic and status propagation.
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main.c: Event loop that tokenizes input, detects logical AND operators (&&), and chains command execution based on success/failure semantics. Manages prompt rendering and interactive state.
- cd [path] Change working directory (no args: go to HOME)
- pwd Print current working directory
- exit Terminate shell
- help Display command reference
- && Logical AND - execute right side only if left side succeeds Example: cd /tmp && ls
make
This compiles all source modules with include path set to the include directory.
./myshell
The shell displays the current working directory in the prompt and continues reading commands until exit is invoked.
The shell forks a child process and executes external commands via execvp(). The parent process waits for completion and propagates exit codes up through the call stack. This enables proper && operator semantics.
This implementation prioritizes clarity over performance. It is intended as an educational reference for understanding shell mechanics, not production use.