Chapter 9 Linux+
To terminate a background process, you can send a kill signal to the PID or to the background job ID prefixed with which character?
%
What is the nice value measured range?
-20 (lower priority number provides a greater chance of a higher priority) 19 (higher priority numer provides a greater chance of a lower priority)
Which argument can be used to display an entire list of processes across all terminals, including daemons?
-e ps -ef
What option lists even more information about each process than the -f option?
-l ps -l
What is the range of a process' priority and what do they indicate?
0 (high priority) - 127 (low)
How many different kill signals are there?
64
If a user starts a process while logged in to a terminal and the process runs in that terminal, what is it labeled as?
A User Process e.g. ls, grep, find
What is a system process that is not associated with a terminal?
Daemon Process (Most startup on system startup, but can be started manually)
(T/F) PIDs given to new processes in sequential order?
False
How is each PID generated?
From free entries in a process table used by the Linux kernel.
What does a ? in the TTY column indicate?
It indicates daemons and kernel processes that do not run on a terminal
What are known as defunct processes?
Zombie processs
What character may be appended to bypass the wait function and send a user process to the background?
ampersand (&)
Which Berkeley-style options (options that do not need to be prefixed by a dash character) lists all processes across terminals and lists processes that do not run on a terminal using the ps command?
as ps ax
What is a process that does not require the BASH shell to wait for its termination and upon execution, the user receives the BASH shell prompt immediately.
background process
Which command moves a foreground process to the background?
bg e.g. bg %1
Each process can start an unlimited number of other processes called?
child process
Which command moves a background process to the foreground?
fg e.g. fg %1
What is a process for which the BASH shell that executed it must wait for its termination?
foreground process
What is the act of creating a new BASH shell child process from a parent BASH shell process?
forking
What does the -f option provide when executed with the ps command?
full
Which command is used to see the list of background processes running in the current shell?
jobs
What command may be used to terminate rogue or zombies processes?
kill
What is the command for displaying all kill signals?
kill -l
What has a PID of 2?
kthreadd
Which command displays a list of processes that are running in the current shell?
ps
Which command displays the lineage of a process by tracing its PPIDs until the init daemon?
pstree
Which command, aside from ps, is the most common program to display processes?
top
What value can be used to affect the process priority indirectly?
Nice Value (NI)
How many PPIDs does each process have?
One
What is the PID of the kernel itself?
PID = 0
What is the PID and PPID of the initialize daemon?
PID = 1 PPID = 0
Each process must have been started by a ?
Parent Process
What identifies the process that started it?
Parent Process ID (PPID)
What is a program that is running in memory and on the CPU?
Process
What allows the kernel to identify each process uniquely?
Process ID (PID)
Which column indicates what the process is doing when the ps -l command?
Process State (S)
What is an executable file on the hard disk that can be run when you execute it?
Program
What is a process that has encountered an error during execution and continuously uses up system resources?
Rogue processes
What does the R and S stand for in the process state column?
Running; Sleeping
What is the name and number of the kill signal which will stop and restart a process with the same PID?
SIGHUP; 1 e.g. kill -1 1199
What is the most common kill signal, also known as the absolute kill signal which forces the linux kernel to stop executing the process by sending the process' resources to a special device file called /dev/null?
SIGKILL; 9 e.g. kill -9 1199 kill -SIGKILL 1199
What is the name and number of the kill signal which terminates a a process by taking the process information in memory and saving it to a file called core on the hard disk in the current working directory, also known as a core dump?
SIGQUIT; 3 e.g. kill -3 1199
What is the most common kill signal used by programs to kill other processes and is the default kill signal used by the kill command?
SIGTERM; 15 e.g. kill -15 1199
What does the T and Z stand for in the process state column?
Stopped; Zombie
How does the kernel measure a process' priority?
The Process priority (PRI)
How is a zombie process killed?
The parent process is killed.