Creating a command-history feature in self-made shell

[itay]

Hello, i've been tasked to create a linux shell using C. every command should run as if it was ran by a standard terminal except the commands "exit" (which was easily implemented) and "history". in history i should print all commands that have been written to the shell (wether they were successful or not) with the PID of the thread that received it:
$ history
123 cd asd
456 ls
123 ls -l
456 cd asdflajfd
456 history
$
assume the shell will receive max 100 commands, each in 100 chars length max.
My question is:
how do I create an "history array" that is shared with all threads and their "sons", in a way that will achieve the task mentioned above?

[john.c]

It seems pretty simple.
Firstly, you do no usually run shell commands in "threads".
You usually run them in separate processes.
The parent process receives the pid of the child (not "son"!), so it's pretty simple to store the pid and command line in an array.
The history array doesn't need to be accessible to the child processes, only to the parent process.