0x16. C - Simple Shell : Collaboration between @drLeenaK and @esianyo
ALL TASKS ARE ON THE GITHUB REPOSITORY: simple_shell
TASK 0 Betty would be proud (mandatory) Write a beautiful code that passes the Betty checks
TASK 1: Simple shell 0.1 (mandatory)
Write 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…
TASK 2 : Simple shell 0.2 (mandatory) Simple shell 0.1 +
- Handle command lines with arguments
** TASK 3** Simple shell 0.3 (mandatory) Simple shell 0.2 +
- Handle the PATH
- fork must not be called if the command doesn’t exist
TASK 4. Simple shell 0.4 (mandatory) 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
TASK 5. Simple shell 1.0 (mandatory) Simple shell 0.4 +
- Implement the env built-in, that prints the current environment
TASK 6. Simple shell 0.1.1 #advanced 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
TASK 7. Simple shell 0.2.1 #advanced Simple shell 0.2 +
You are not allowed to use strtok
TASK 8. Simple shell 0.4.1 #advanced Simple shell 0.4 +
handle arguments for the built-in exit
- Usage: exit status, where status is an integer used to exit the shell
TASK 9. setenv, unsetenv #advanced Simple shell 1.0 +
Implement the setenv and unsetenv builtin commands
setenv
- Initialize a new environment variable, or modify an existing one
- Command syntax: setenv VARIABLE VALUE
- Should print something on stderr on failure unsetenv
- Remove an environment variable
- Command syntax: unsetenv VARIABLE
- Should print something on stderr on failure
TASK 10. cd #advanced Simple shell 1.0 +
Implement the builtin command cd:
- Changes the current directory of the process.
- Command syntax: cd [DIRECTORY]
- If no argument is given to cd the command must be interpreted like cd $HOME
- You have to handle the command cd -
- You have to update the environment variable PWD when you change directory man chdir, man getcwd
TASK 11. ; #advanced Simple shell 1.0 +
- Handle the commands separator ;
TASK 12. && and || #advanced Simple shell 1.0 +
- Handle the && and || shell logical operators
TASK 13. alias #advanced Simple shell 1.0 +
- Implement the alias builtin command
- Usage: alias [name[='value'] ...]
- alias: Prints a list of all aliases, one per line, in the form name='value'
- alias name [name2 ...]: Prints the aliases name, name2, etc 1 per line, in the form name='value'
- alias name='value' [...]: Defines an alias for each name whose value is given. If name is already an alias, replaces its value with value
TASK 14. Variables #advanced Simple shell 1.0 +
- Handle variables replacement
- Handle the $? variable
- Handle the $$ variable
TASK 15. Comments #advanced Simple shell 1.0 +
- Handle comments (#)
TASK 16. File as input #advanced Simple shell 1.0 +
Usage: simple_shell [filename]
- Your shell can take a file as a command line argument
- The file contains all the commands that your shell should run before exiting
- The file should contain one command per line
- In this mode, the shell should not print a prompt and should not read from stdin
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