Sec. 2 Processes

Question 1

a program is a ……?

Answer 1

set of instructions, along with any internal data used while carrying in the instructions out.

Question 2

a program may also use ….?

Answer 2

external data

Question 3

what is a process?

Answer 3

a process is an executing program and associated resources .

• including :
  
  • enviorment open files
  • signal handlers
  • etc…

Question 4

when it comes to an everything is shared situtation with processes one speaks of …..?

Answer 4

multi-threaded process

Question 5

In linux each thread of execution is considered …..?

Answer 5

individually

Question 6

describe what a process is:

Answer 6

A process is an instance of an executing program .

Question 7

every process has a ….?

Answer 7

process id or pid, a ppid or parent process id and a pgid (process group id)

Question 8

every process also has ……?

Answer 8

• program code
• data
• variables,
• file descriptors
• and an evironment

Question 9

init is usually the first _______ ?

Answer 9

process run ona system.

Question 10

if the parent process dies before the child the ppid of the child is set to …..?

Answer 10

1

Question 11

the child process which dies before its parent is known as a ….?

Answer 11

zombie process

Question 12

Zombie processes have released all of their resoures and remain only to …..?

Answer 12

convey their exit status

Question 13

processes are controlled by …..?

Answer 13

scheduling

Question 14

Scheduling of processes is completely ….?

Answer 14

preemptive

Question 15

All process have certain attributes . what are they?

Answer 15

• the program being executed
• context (state)
• permissions
• associated resources

Question 16

every process is executing some …….?

Answer 16

program

Question 17

explain what the context of a process is .

Answer 17

at any given moment , a process may taek a snapshot of itself by trapping the state of its CPU registers, where it is executing in the program, what is in the process’ memory and other information. this is the processs’ context

Question 18

when a process started it is isolated in it own ______ ______ to protect is from other processes .

Answer 18

user space

Question 19

do processes have direct acces to hardware?

Answer 19

no

Question 20

Hardware is managed by the ……?

Answer 20

kernel

Question 21

a process will have to use (what?) to indirectly access hardware

Answer 21

system calls

Question 22

system calls are the fundamental interface between (what?) and the (what?)

Answer 22

application, kernel

Question 23

ulimit

Answer 23

ulimit is a built in bash command that displays or resets a number of resource limits associated with processes running under the shell.

Question 24

using ulimit how would see what is running?

Answer 24

ulimit -a

Question 25

when using **ulimit** there are two types of limits . what are they?

Answer 25

1. **hard** and 2. **soft**

Question 26

define the **hard** limit:

Answer 26

* the **hard** limit: * the **maximum** value , set only by the **root user**, that a user can raise the resource limit to . * example : * **ulimit -H -n**

Question 27

define the **soft** limit:

Answer 27

* **soft** limit: * the current limiting value, which the user can modify, but cannot exeed the hard limit.

Question 28

what is the syntax of the command **ulimit**

Answer 28

**ulimit [option] [limit]**

Question 29

changes made with **ulimit** only affect the current **shell** if i want to make the changes effective for all users I would need to modify what **file?**

Answer 29

**/etc/security/limits.conf**

Question 30

**processes** can be one of several .......?

Answer 30

states

Question 31

define the **process** state : **running**

Answer 31

* **process state: running** * **​**the **process** is either currently executing on a *CPU* or *CPU core* or sittingin thr **run queue,** eargerly awaiting a new *time slice*. * it will resume running when the *scheduler* decides it is now deserving to occupy the *CPU,* or another *CPU* becomes idle

Question 32

**du**

Answer 32

* Name: * **du** ---- estimate file space usage * synopsis: * **du** -- [**option**] ... [**file**] ... * Discription: * *summarize disk usage of the set of files, recursively for directories .*

Question 33

## Footnote **du --all**

Answer 33

writes count ofr all files , not just directories.

Question 34

**du --apparent-size**

Answer 34

print apparent sizes , rather that disk usage; although the apparent size is usually smaller, it may be larger du to holes in files....

Question 35

**du --c , --total**

Answer 35

will produce a grand total of the disk summary usage

Question 36

**du --d; --max-dept=N**

Answer 36

print the total for a directory only if if is N or fewer levels below teh comand line arguement. **--max-depth=0** is the same as **--summarize** **--maxdepth=1**: Just go down one level from **/** and sum up everything recursively underneath in the tree.

Question 37

**du -h ; --human-readable**

Answer 37

du's output will print sizes in human readable format e.g. , 1k ,234 M...

Question 38

**du --inodes**

Answer 38

will list inode usage instead of block usuage

Question 39

**du --time**

Answer 39

show time of the last modification of any file in the directory, or any of it subdirectories

Question 40

**du --X , --exclude-from=File**

Answer 40

exclude files that match any pattern in **File**

Question 41

**du -x ; --one-file-system**

Answer 41

skip directories on different file systems **-x** Stay on one filesystem ; don’t look at directories that are not on the **/** partition. In this case that means ignore: **/dev /proc /run /sys** because these are **pseudo-filesystems(/dev /proc /run /sys)** which exist in memory only; they are just *_empty mount points_* when the system is not running.

Question 42

To obtain a full list of directories under **/** along with their size:

Answer 42

$ ***sudo du --max-depth=1 -hx /***

Question 43

**ulimit -S**

Answer 43

**-S** , specifies the soft limit

Question 44

**ulimit -H**

Answer 44

**-H** , specifies the hard limit

Question 45

## Footnote **ps**

Answer 45

* Name: **ps** * **​ps -** *[options]* * Discription: * **ps** displays information about a *selection* of the *active processes*

Question 46

**ps -e**

Answer 46

see every process on the system using standard syntax

Question 47

by default , **ps** selects all processes with the same effective _________ as the current user and associated with the same terminal as the invoker. .

Answer 47

user ID

Question 48

**ps** works by reading the _____________ ?

Answer 48

virtual files in **/proc**

Question 49

# ps -o option : **cgroup**

Answer 49

display control groups to which the process belongs

Question 50

# ps -o option : **cgroup**

Answer 50

display control groups to which the process belongs

Question 51

# ps -o option : **cgname**

Answer 51

display name of control groups to which the process belongs

Question 52

# ps -o ## Footnote *option : **c***

Answer 52

processor utilization. Currently , this is teh integer value of the percent usage over the lifetime of the process

Question 53

# ps -o *option :* **blocked**

Answer 53

mask of the blocked signals. according to the width of teh field, a 32 or 64-bit mask in hexadecimal format is displayed