/simple_shell

Writing a simple UNIX command interpreter.

Primary LanguageC

PROJECT: 0x16. C - Simple Shell

This project is a collaborative project carried out by: JIMMY MKPOIKANA (https://github.com/Mkpos) & ONABOWALE SIMEON (https://github.com/XimeonLeo) Date: 10th May, 2023. Cohort: 13

OUTPUT:-

  • Unless specified otherwise, your program must have the exact same output as sh (/bin/sh) as well as the exact same error output.
  • The only difference is when you print an error, the name of the program must be equivalent to your argv[0]

List of allowed functions and system calls

'''

***
- access (man 2 access)
- chdir (man 2 chdir)
- close (man 2 close)
- closedir (man 3 closedir)
- execve (man 2 execve)
- exit (man 3 exit)
- exit (man 2 _exit)
- fflush (man 3 fflush)
- fork (man 2 fork)
- free (man 3 free)
- getcwd (man 3 getcwd)
- getline (man 3 getline)
- getpid (man 2 getpid)
- isatty (man 3 isatty)
- kill (man 2 kill)
- malloc (man 3 malloc)
- open (man 2 open)
- opendir (man 3 opendir)
- perror (man 3 perror)
- read (man 2 read)
- readdir (man 3 readdir)
- signal (man 2 signal)
- stat (__xstat) (man 2 stat)
- lstat (__lxstat) (man 2 lstat)
- fstat (__fxstat) (man 2 fstat)
- strtok (man 3 strtok)
- wait (man 2 wait)
- waitpid (man 2 waitpid)
- wait3 (man 2 wait3)
- wait4 (man 2 wait4)
- write (man 2 write)
***

'''

## Compilation:-
Your code should compike this way;
* gcc -Wall -Werror -Wextra -pedantic -std=gnu89 *.c -o hsh

'''

TASKS:-

0. Betty would be proud

Write a beautiful code that passes the Betty checks

'''

##1. Simple shell 0.1 Write a UNIX command line interpreter. 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

'''

4. 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

'''

5. Simple shell 1.0

Simple shell 0.4 +

* Implement the env built-in, that prints the current environment

'''

6. Simple shell 0.1.1

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

'''

7. Simple shell 0.2.1

Simple shell 0.2 +

* You are not allowed to use strtok

'''

8. Simple shell 0.4.1

Simple shell 0.4 +

* handle arguments for the built-in exit
* Usage: exit status, where status is an integer used to exit the shell

'''

9. setenv, unsetenv

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

'''

10. cd

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

'''

11. ;

Simple shell 1.0

* Handle the commands separator ;

'''

12. && and ||

Simple shell 1.0 +

* Handle the && and || shell logical operators

'''

13. alias

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

'''

14. Variables

Simple shell 1.0 +

* Handle variables replacement
* Handle the $? variable
* Handle the $$ variable

'''

15. Comments

Simple shell 1.0 +

* Handle comments (#)

'''

16. File as input

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.