Process Management in UNIX
UNIX supports two types of processes:
1. System Process – It runs in kernel mode and execute the operating system functions.
2. Usf Process – It runs in the background mode.
Process States in UNIX:
The lifetime of a process can be conceptually divided into 9 states.
1. User Running: The process is executing in user-mode.
2. Kernel Running: The process is executing in the kernel-mode.
3. Ready to run: The process isn’t executing, but it is ready to run as soon as the kernel schedules it.
4. Asleep: The process is sleeping and resides in the main memory.
5. Ready to run, Swapped: The process is ready to run, but the swapper must swap the process into the main memory before the kernel can schedule it to execute.
6. Sleeping, Swapped: The process is sleeping, and the swapper has swapped the process to secondary storage to make room for other processes in the main memory.
7. Preempted: The process is returning from the kernel to user mode but the kernel preempts it and it does a context switch to schedule another process.
8. Created: The process is newly created and not yet ready to run.
9. Zombie: The process is no longer exists, but it leaves a record for its parent process to collect.