This Project focus on building a simple UNIX shell program.

This is a requirement to implement the knowledge of C programming basics. This project contains defined user functions, do similar work compared to the same library function, example: copy-string does the work of strcpy. The project consist of files, all sums up the step by step function of a shell program.

Program Breakdown

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• 1. Handle many attributes of the shell yet.
• 2. This step Handle command lines with arguments, unlike the first, that only reads and prints out user input.
• 3. This step handle the PATH, which is the list of all directories, a shell access to executes a particular command.
• 4. This part implements the exit built-in that exits the shell. From the previous steps, the shell can not exit.
• 5. This step implement the env built-in that prints the current enviroment.
• 6. At this stage, we write a function that reads input from the command line, this function mimics the getline library function.
• 8. This step handle arguments for the built-in exit. Exit status also allowed at this point.
• 9. This step implemets the setenv and unsetenv built-in commands.
• 10. This step implement the builtin command cd.
• 11. This step handles the commands separator ; which is a sequencing character.
• 12. This step handles the && and || shell logical operators.
• 13. This step implemets the alias built-in command.
• 14. This step handles variables replacement; that is $ variable.
• 15. Commenting # is handled at this stage.
• 16. This step handle the usage of simple_shell [filename]