My first big project using C. A Unix command line interpreter using OS concepts such as fork, wait, and exec. Uses all linux commands such as ls, cd, mv, grep, etc..

Features:
I/O redirection using ">" and "<"
Pipelining using "|" on two commands
backgrounding a process using "&" with the command
running a process in the background using "bg" foregrounding the most recent process using "fg"

##Compilation
Type "make" with all of the source files in the folder using a C compiler (clang) and type my-sh to run.

##Description (how it works) Mainly, the code will start at my-sh and wait for user input - once it is given, the tokenizer will parse the input and put each token into appropriate places - the two parts of the pipe and the in/out filenames. It also takes note of whether there is an ampersand, a pipe, or if the command was fg or bg. Then, it passes all of this information into the execute function.

The execute function handles the basic forking/exec-ing. It also takes into consideration all of the extra details like I/O, pipe, and background. It will then wait for the current foreground process passed in (if there was one), and then wait for any background processes to harvest before exiting.

In the case of I/O, it will open/dup2 the appropriate files

In the case of pipe, it will fork a second child process for the right side of the pipe along with any I/O that needs to be done

In the case of an ampersand, it will bypass the foreground waiting and simply add the process to the list to keep track of.

In the case of bg - it will scan the list of background processes for the first one stopped. Because it is a stack, the first one that it comes across is the one that was most recently stopped and inserted into the list. It then gives that process SIGCONT

In the case of fg - it will also scan the list for the first bg process stopped - if there isn't one, it will just take the first process on the list since it is the most recent job. Whichever of the two happens, it will pass on the signal, give it terminal control, and then wait for that job to finish.