A custom shell implemented in C that supports executing commands, handling environment variables, and built-in commands like setenv, unsetenv, exit, and echo. It provides a basic interactive shell interface where you can enter commands and receive output.

• Execute external commands and handle built-in commands.
• Environment variable management with setenv and unsetenv commands.
• Handle special environment variables like $? and $$.
• Replace environment variables in strings using the $ syntax.
• Basic error handling and memory management.

The custom shell supports basic shell commands and built-in commands. You can execute external commands and use the built-in commands by typing them into the shell.

To compile the shell, run

gcc -Wall -Werror -Wextra -pedantic -std=gnu89 *.c -o hsh

Example of built-in commands:

• echo [text]: Display text to the console.
• setenv [variable] [value]: Set or update an environment variable.
• unsetenv [variable]: Remove an environment variable.
• exit [status]: Exit the shell with an optional status code.

To execute external commands, simply type the command name followed by any required arguments.

• Built-in commands are handled within the shell program.
• Environment variable expansion is supported using $VARNAME syntax.

Feel free to explore this custom shell implementation according to your needs!