0x16. C - Simple Shell
Building My Own Shell
Tasks 0. Betty would be proud a beautiful code that passes the Betty checks
- Simple shell 0.1
a UNIX command line interpreter.
Usage: simple_shell
Your Shell should:
Display a prompt and wait for the user to type a command. A command line always ends with a new line.
The prompt is displayed again each time a command has been executed.
The command lines are simple, no semicolons, no pipes, no redirections or any other advanced features.
The command lines are made only of one word. No arguments will be passed to programs.
If an executable cannot be found, print an error message and display the prompt again.
Handle errors.
You have to handle the “end of file” condition (Ctrl+D)
You don’t have to:
use the PATH
implement built-ins
handle special characters : ", ', `, \, *, &, #
be able to move the cursor
handle commands with arguments
execve will be the core part of your Shell, don’t forget to pass the environ to it… 2. Simple shell 0.2 Simple shell 0.1 +Handle command lines with arguments 3. Simple shell 0.3
Simple shell 0.2 +
Handle the PATH
fork must not be called if the command doesn’t exist
- Simple shell 0.4
Simple shell 0.3 +
Implement the exit built-in, that exits the shell
Usage: exit
You don’t have to handle any argument to the built-in exit
- Simple shell 1.0
Simple shell 0.4 +
Implement the env built-in, that prints the current environment
- Simple shell 0.1.1
Simple shell 0.1 +
Write your own getline function
Use a buffer to read many chars at once and call the least possible the read system call
You will need to use static variables
You are not allowed to use getline
You don’t have to:
be able to move the cursor