Process.new(-1).exists? returns true in Linux

[joaodiogocosta]

While trying to initialize a variable that represents a pid to something I thought was safe (an Integer that could never be a valid pid), I ended up killing my VM by doing:

pid = -1 # Invalid pid
Process.new(pid).exists? # returns true
Process.new(pid).kill # kills all processes in my Linux VM

Then I found that kill -9 -1 also kills my Linux VM. Possibly related Stack Overflow thread.

Even if Process.new(-1).kill is intended behaviour, should Process.new(-1).exists? return true?

[asterite]

The initialize method of Process is defined as protected, but that's the default visibility status, so that new becomes public. It's probably a bug in the compiler. I will mark it as private. You shouldn't be able to instantiate a process by pid like that.

[zatherz]

Just to provide more context on why this had the effect that it had - PID -1 is a special case. Trying to kill it results in everything except the kill process itself and init being killed.