EnvironmentVariablesExplained.txt

Environment Variables Explained
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This is how I think env variables work:

- When shell process is started, the parent OS environment variables are copied into the process.
- When your shell calls getenv() or setenv(), it is modifying the process copy NOT the parent copy.
- Shells can maintain a local copy of the environment variables as well which will be instantiated in shell_init()
- These local copies must be updated whenver the process copies are also updated.  
- Updating the local copies without updating the process copy may cause problems for forked processes.
- I have no clue what a forked process is



- A forked process is one that is identical to the process that called fork()
	i.e. process 1 calls fork(), it creates a child process that it identical to the parent (the caller process)
- syscall fork() returns either negative value, zero, or posititve value
	- negative value is returned if child process could not be created
	- zero is returned to the child process
	- positive value (also the pid of the child process) returned to the parent process
- after creation of the child process, both processes work independently of each other
	- however, they BOTH execute the next line of code