Mateo Notes

When we type:

./hello

it feels like something very simple happens.

We execute a file, and suddenly a program is running.

But from the operating system's point of view, there is a lot more going on.

This post is a small journey from a command in the shell to a running process.

---

1. The Shell

First, the shell receives our command:

./hello

The shell doesn't magically execute the file itself.

A typical Unix shell creates a new process and asks the operating system to replace that process's program image with the requested executable.

One important system call involved here is:

execve();

For example:

char *argv[] = {
    "./hello",
    NULL
};

execve("./hello", argv, NULL);

The interesting thing about execve() is that