iterate shell

This is iterate project for C/C++ experience; we are making a UNIX
shell, this will NOT work on Windows but it will work on OS X and
any other UNIX aka any Linux.

Your code should be implemented in the .cpp files with an
appropriate API exposed in the respective .h file.

requirements per platforms

OS X

Congrats, on OS X you don’t need to do anything other than have
XCode installed.

Linux

The project uses clang and the fsanitize so you’ll need to have
these installed on your machine, use aptitude

$ aptitude install libc++1 clang lldb make libasan1 libasan1-dbg libasan0

For Linux a convenience Makefile target has been added to get all
the needed dependencies, just do:

$ make install_dependencies

Windows

Your options are:

1. Get rid of Windows, install Linux (Debian or Ubuntu is good)
2. Dual boot Linux and Windows
3. Get a Virtual Machine on Windows, can use VMWare or Virtual Box.

Development Roadmap (Always check for updates as this is always updating)

First steps, getting input, parsing

A shell is a REPL, which stands for: READ EVALUATE PRINT LOOP. It
takes a line of input, evaluates it, prints the results and loops
again. So the first step is to write code that takes a line of input
from the user. Once you get that line of input, you need to parse
it, that is turn it into something understand about. Take for example:

$ git status

What will your shell really read in?

*HINT: How much should you keep reading?
When do you stop reading from `stdin`?*

You shell will get:

"git status"

And this isn’t useful yet. You need to split the string into different
parts. Remember that many programs have short flags and long flags,
aka - and --.

*HINT: Read about shell redirection, you will need to handle the
special symbols |, <, and >

Once you have that all together, you need to think about process
management.

Process management

Unix process management is a hierarchieral relationship. When we start
a prorgram, say git, we have this relationship.

bash
  |--git

That is, bash is the parent of git. You can see the entire process
tree with

$ pstree

If you don’t have pstree then use aptitude to install it,
$ aptitude install pstree.

Testing the shell

You should be invoking iterate_shell as so:

$ make test_shell

You should also run the automated test suite with:

$ make run_tests

YOU MUST run this before submitting any Pull Request.

System calls you are expected to use

These are C system calls that you are expected to use in this project:

execve (To execute the program)
waitpid (To make the parent wait for the child)
fopen (To read a startup script)
fork (To create a new process)
stat (To check if a file exists)
fread (To read from a file)

Remember you can always find more details in their respective man
pages, for example you can do in the shell:

$ man 2 execve