When the system boots up, the first process with PID=1 starts, which is systemd - it is usually a symbolic link to "/sbin/init" -.
This parent process spawns other processes, which in turn spawn others with higher PID numbers.
The PID on a system can't go beyond a certain number defined in the file "/proc/sys/kernel/pid_max".
We could check this value using the below command:
We could change the pid_max value to 20000 using the below command:
We could do it also by writing the value directly in the below file:
When the maximum number of PID is reached, the system goes back to using the lowest values available.