Command Line and Exit code

The simplest IPC method is:
Command-line parameter passing
Parameters are arbitrary strings
The command line can be many kilobytes long
stdin/out/err as already-opened files
The new process can receive commands or data
The new process can send commands or data
Environment variables for configuration parameters
The child inherits the parent's environment
We can even avoid the command line altogether
The return value received through _exit(2)
0 is generally used to mean "success"
Other values (1-255) mark specific errors
The parent can know if the child was killed
Example: wor0if, worif

  fork(2), execve(2), _exit(2), wait(2)