Chapter 9-Managing Linux Processes

To display an entire list of processes across all terminals and including daemons, you can add the ____ option to any ps command.

-e

Each process can start an unlimited number of other processes called _______.

child process

The cron daemon is better suited for repetitive tasks because it uses configuration files called ____________ to specify when a command should be executed.

cron tables

To create or edit a user cron table, you can use the -e option to the ______________, which opens the vi editor.

crontab command

Because __________________ are not associated with a terminal, they are not displayd by the ps -f command.

daemon processes

Process genealogy

figure 9-2 page 463

After a background process has been started, you can move it to the foreground by using the _________________ followed by the background job ID.

foreground(fg) command -you can pause a foreground process by using the Ctrl + z key cobination.

When executing compiled programs or shell scripts, the BASH shell that interprets the command you typed creates a new BASH shell. This creation of a new subshell is known as ___________ and is carried out by the fork function i the BASH shell.

forking

The first process started by the Linux kernel is the ________________________, which has a PID of 1 and a PPID of 0, the latter of which refers to the kernel itself.

initialize (or init) daemon

After a process has been started, you can use the ps command to view the PID or the _______________ to view the background job ID.

jobs command

Another command that can be used to send kill signals to processes is the ______________.

killall command.

foreground process

A process for which the BASH shell that executed it must wait for its termination.

background process

A process that runs "behind the scenes" with a low priority, does not require input, and rarely creates output. (11)

You can execute three main types of Linus commands:

Binary programs Shell scripts Shell functions

A system process that is not associated with a terminal, is called a ______________. These processes are typically started on system startup, but you can also start them manually.

Daemon process

The ______________ can be used to affect the process priority indirectly; it is measured between -20(a greater chance of high priority) and 19(a greater chance of lower priority).

Nice value (NI)

_______________ is the priority used by the kernal for the process; it is measured between 0(high priority) and 127(low priority).

Priority process(PRI)

kill command

The command used to kill or terminate a process.

kill signal

The type of signal sent to a process by the kill command; different kill signals affect processes in different ways.

To schedule a command or set of commands for execution at a later time by athe at daemon, you can specify the time as an argument to the ____________/

at command.

You can use two different daemons to schedule commands: the ______________ and the ________________.

at daemon (atd) cron daemon (crond) -the at daemon can be used to schedule a command to execute once in the future, whereas the cron daemon us used to schedule a command to execute repeatedly in the future.

You can send the process to the background with the ___________________.

background(bg) command

Commands such as cd and exit, are built into the ________________ running in memory.

bash shell

Most commands such as ls, find, and grep are _________________ that exist on the filesystem until executed.

binary programs

The init daemon is often referred to as the _______________ of all user processes.

"grandfather"

you can use the __________________ command to view the files that a process has open before sending a SIGKILL.

lsof(list open files)

To start a process with a nice value of +19(low priority), you can use the ________________ and specify the nice value using the ____________ and the command to start.

nice command -n option

To prevent a child process from being terminated when the parent process is terminated, you can start the child process with the ______________.

nohup command

Each process must have been started by an existing process called a _____________.

parent process

As a result, each process has a ___ which identifies the process that started it.

parent process ID (PPID)

When sending a kill signal to several processes, it is 0ften easier to locate the process PIDs using the _____________.

pgrep command -returns a list of PIDs for processes that match a regular expression, or other criteria.

You can also use the ___________________ to kill processes by process name.

pkill command -the pkill command allows you to identify process names using regular expressions as well as specify other criteria.

A ___________ is a program that is running in memory and on the CPU.

process i.e. -A process is a program in action

Every process as a unique _________________ that allows the kernel to identify it uniquely.

process ID(PID)

The ______________ column is the most valuable to systems administrators because it indicates what the process is currently doing.

process state (S)

A ______________ is an executable file on the hard disk that can be run when you execute it.

program

The _______________ lists the Linux kernel priority (PRI) of a process.

ps -l

Although several Linux utilities can view processes, the most versatile and common is the ________________.

ps command

Without arguments, the ___ command simply displays a list of processes that are running in the current shell. It includes the PID, terminal, CPU time and the command that started the process.

ps command

The ____________ displays the lineage of a process by tracing its PPIDs until the init daemon.

pstree command

After a process has been started, you can change its priority by using the _________________ and specifying the change to the nice value, as well as the PID of the processes to change.

renice command

You might come across a process that has encountered an error during execution and continuously uses up system resources. These processes are refered to as _________________ and appear at the top of the listing produced by the _____________________.

rogue process; top command

Common options to the ps command

table 9-1 page 469

Common administrative kill signals

table 9-2 page 473

The amount of time a process has to use the CPU is called a ____________, the more time slices a process has, the more time it has to execute on the CPU and the faster it executes.

time slice.

The ____________ displays an interactive screen listing processes organized by processor time.

top command -The most common program used to display processes, aside from ps.

Some processes have the ability to ignore, or __________, certain kill signals that are sent to them.

trap

If you start a process while logged in to a terminal, that process runs in that terminal and is labeled a ____________.

user process Examples: -ls, grep and find

The ________________ can be used instead of the cron daemon for scheduling very frequent tasks.

watch command

On a busy Linux server, _____________ can accumulate and prevent new processes from being created; if this occurs, you can kill the parent process of the zombies.

zombie process

You might also see a Z in this column, indicating a _____________.

zombie process