Processes

The Linux kernel is the core of a Linux installation. The kernel manages memory, provides software with a way to access the hard disk, doles out CPU time, and performs other critical low-level tasks. The kernel is loaded early in the boot process, and it's the kernel that's responsible for managing every other piece of software on a running Linux computer.

More about processes

Normally at boot, one process is started /sbin/init. Then everything else is managed by init and are called child processes. (sometimes also referred to as daemons)

Internally, the kernel maintains process information in the process table . Tools such as ps and top (described shortly) enable you to view and manipulate this table.

Process ID numbers

Every process has a PID. Init's id is normally 1. Each process also has a parent process id(PPID).

• ps aux --forest can help show parent/child relationships

More on Processes

• kill: find the pid and issue the command
• We can also send it a signal like kill -9 PID
• killall: kills by process name instead of pid
• example: killall -9 testme

Process related commands

• ps , ps aux
• fg
• bg
• control + z
• jobs
• top
• & # to run in background
• sleep

Process states

Process Signals

Messages sent between processes. A numeric value.

Names:

• interrups (Cntrl + c)
• sleep (Cntrl + z)
• kill
• etc..

Process related files

• /proc/cpuinfo
• /proc/meminfo