Linux mod 5

Question 1

A program that provides text only interface for Linux and other UNIX like OSs.

Presents each user with a prompt, executes user commands and supports a custom environment for each user.

Answer 1

Shell

Question 2

What does the # symbol indicate in

[root@Linux ~]#

Answer 2

Root user

Question 3

What does the $ or % indicate

[bob@localhost ~]$

Answer 3

Non-root user

Question 4

What are the different shells available?

Answer 4

Bourne Shell (sh)
Tenex C Shell(tcsh)
C Shell (csh)
Bourne-Again Shell (bash)

Question 5

Display on-line manual pages about command.

Answer 5

man

Syntax: man

Question 6

Clears the current screen

Answer 6

clear

Question 7

Print working directory, displays the current working directory.

Answer 7

pwd

Question 8

Displays the UNIX OS variant.

Answer 8

uname

uname -a Prints all information

Question 9

Prints or sets the system date and/or time.

Answer 9

date

date -s
Sets date to date and time provided.

Question 10

Lists directory contents in a tree-like format.

Answer 10

tree

tree -c Turn colorization on
tree -f Append a “/“ for directories

Question 11

Exit the current shell

Answer 11

exit

Question 12

Lists contents of a directory

Answer 12

ls
ls -l Long-list - shows ownership, permission, and links.
ls -i Inode number in the first field
ls -s number of file system blocks
ls -a List all files including invisible files

Question 13

What are text files are viewed using text viewer utilities?

Don’t change file contents but allow forward and backward navigation as well as search.

Answer 13

Pagers

Question 14

Displays text files one screen at a time.

Answer 14

less
Options: -b Backwards movement, one page at a time
/ Initiates a search for a string (word)
q Exits from less
SPACE BAR Advances one screen at a time
ENTER Key Advances one line at a time

Question 15

Works like the less command but with fewer options.

Answer 15

more

Question 16

Automatically prints the first 10 lines of a file to standard output.

Answer 16

head

Syntax: head

Question 17

Command automatically displays the last 10 lines

Answer 17

tail

Syntax: tail

Question 18

Displays file(s) contents to the screen and can concatenate (combine) files.

Answer 18

cat

Syntax: cat
cat >

Question 19

Change directory

Answer 19

cd
Syntax: cd //
cd

Question 20

Static files of the boot loader; required to boot the system.

Answer 20

/boot

Question 21

Essential command binaries (e.g., cp, mkdir, ls, less).

Answer 21

/bin

Question 22

Essential system binaries. Commands intended for use by privileged users.
(e.g., init, fdisk, ifconfig, lsmod).

Answer 22

/sbin

Question 23

Second major hierarchy. User system resources, i.e., user binaries, and associated documentation, libraries, and header files

Answer 23

/usr

Question 24

Shared libraries.

Answer 24

/lib

Question 25

Device files (block and character).

Answer 25

/dev

Question 26

System administration and configuration files.

Answer 26

/etc

Question 27

User home directories.

Answer 27

/home

Question 28

Optional third-party software.

Answer 28

/opt

Question 29

Processes used by system.

Answer 29

/proc

Question 30

Root user's home directory.

Answer 30

/root

Question 31

Temporaru files used by the system

Answer 31

/tmp

Question 32

Variable size data like that found in log files

Answer 32

/var

Question 33

In UNIX, the | current working directory is displayed using the ___ (print working directory) command.

Answer 33

pwd

Question 34

The _______ is based on the present working directory.

Answer 34

relative path

Question 35

An _______ in UNIX begins at the root ( / ) directory.

Answer 35

absolute path

Question 36

Displays text to standard output.

Answer 36

echo Syntax: echo

Question 37

The path statement is modified using the ____ command

Answer 37

PATH Example:[root@localhost etc]# PATH=$PATH:/usr/demo [root@localhost ~]# echo $PATH

Question 38

All UNIX variances come with a visual editor pre-installed.

Answer 38

vi normally supplied with all UNIX systems requires very little memory uses standard alphanumeric keys for commands Syntax vi

Question 39

Which modes does vi have?

Answer 39

There are only two modes of operation in the vi editor: Command Mode Characters typed perform actions like moving the cursor, cutting or copying text, or searching for a particular text string. vi opens in command mode. Insert Mode Actual text is typed or overwritten.

Question 40

Insertion commands for vi:

Answer 40

i Insert before cursor a Append after cursor o Insert below current line O Insert above current line yy Copy line into memory (yank-yank) p Works with yy to place copied line onto the existing or next line 5p Places five lines of what was copied, at cursor

Question 41

Deletion commands

Answer 41

x Delete current character r Replace current character dd Delete current line

Question 42

Navigation commands

Answer 42

h Move cursor one place to the left l (lower case L) Move cursor one place to the right j Move cursor one place down k Move cursor one place up / Searches within the document for a string

Question 43

Exit commands

Answer 43

:w Writes (saves) latest changes to the file :q Quits, leaving vi open in command mode :q! Quits vi without saving changes :wq! Saves file and any changes, and quits vi.

Question 44

Creates an empty file and is also used to modify a files timestamp.

Answer 44

touch Options: -a Manipulates the file’s access date/time stamp Syntax: touch touch -a YYMMDDHHMM

Question 45

Creates one or more directories

Answer 45

mkdir Options: -p Creates a directory where no parent exists (nested) Syntax: mkdir mkdir -p //

Question 46

Copies files and directories

Answer 46

Options: -r Recursively copy directories. Syntax: cp cp –r

Question 47

Moves or renames files and directories.

Answer 47

mv | Syntax: mv

Question 48

Creates a link between files and directories.

Answer 48

ln Options: -s Creates a symbolic link to another file. Syntax: ln -s

Question 49

Removes a file or a directory with contents if using the -r option.

Answer 49

rm Options: -r Remove a directory and its contents recursively -f Ignore nonexistent files, never prompt (force). Syntax: rm rm -rf

Question 50

Searches a file or files for lines that contain strings of a certain pattern.

Answer 50

grep | Syntax: grep

Question 51

Locates files having certain specified characteristics.

Answer 51

find | Syntax: find -

Question 52

Displays full path (location) or most (shell) commands.

Answer 52

which | Syntax: which

Question 53

Determines file type

Answer 53

file | Syntax: file

Question 54

Displays a snapshot status of active processes. A process running in the background is called a daemon.

Answer 54

``` ps Options: -e Lists information about every process running -l Displays in a long format -f Generates a list in full mode format Syntax: ps -elf ```

Question 55

Stops a process from running using its PID

Answer 55

kill Options: -9 Used to kill a stubborn process that won’t die Syntax: kill [option]

Question 56

Stops a process from running using its process name.

Answer 56

pkill Options: -9 Used to kill a stubborn process that won’t die. -HUP Used to immediately re-spawn a process to effect configuration changes. After modifying a daemon’s configuration file, use pkill -HUP to hang up and restart the daemon with the new configuration. Syntax: pkill [option]

Question 57

Maintains a history file of all commands run by a particular user in that shell.

Answer 57

history history is also used to run previous commands by using an exclamation point (!) followed by the corresponding line number in the history output. Syntax: !

Question 58

Prints the strings of printable characters in a file (not ASCII characters). Useful in determining contents of nono-text files (executables)

Answer 58

strings strings

Question 59

Creates a typescript of the terminal session (everything printed on the terminal). CTRL+d ends the script session. View results using less.

Answer 59

script script

Question 60

Used to switch from the current user account to another. It is often used to switch to root user to perform tasks requiring elevated privileges.

Answer 60

su su

Question 61

Displays who the user is logged in as at this moment (after switching user)

Answer 61

whoami Syntax: whoami

Question 62

Displays user login information including login name, time, terminal, and more.

Answer 62

who Syntax: who

Question 63

Displays information about the user(s) logged in and what they are doing

Answer 63

w

Question 64

_________is used on audio data because some | portions of the data can be thrown away without significant degradation of sound quality.

Answer 64

Lossy Compression

Question 65

______compression creates a file smaller than the original that can later be reconstructed, maintaining all of its data and metadata.

Answer 65

Lossless

Question 66

Compresses files and appends a .gz file extension. The original file is replaces.

Answer 66

gzip Syntax: gzip

Question 67

Decompresses a file that was compressed with gzip.

Answer 67

gunzip | Syntax: gunzip

Question 68

The tape archive ___ command is an archiving utility that has been around since the early days of UNIX and was designed to archive data to a tape drive.

Answer 68

tar

Question 69

Tape archive utility used to archive files to tape or disk.

Answer 69

tar Options: c Create an archive t List table of contents of tar file x Extract, must be in target directory to extract z Compress the archived file using gzip (tarball) v Verbose, list each file as tar reads/writes f Read/write to or from a file C Change to directory Syntax: tar -[options]

Question 70

Schedules a job/process for a one-time execution.

Answer 70

at Syntax: at ENTER at> [CTRL+d] Places the job into the queue and exits

Question 71

Lists user's pending jobs.

Answer 71

atq

Question 72

Deletes user's jobs identified by job number.

Answer 72

atrm

Question 73

Schedules periodic jobs. The cron daemon (crond) checks the /etc/crontab every minute for any jobs that need to run. To create a cron job, the cron table (crontab) is created or modified.

Answer 73

crontab Options: -e Edit the crontab -l List crontab entries

Question 74

Creates a new user or updates default new user information.

Answer 74

useradd Options: -d Specifies the path of the user’s home directory; Linux - users’ home directories are in /home -m Makes a home directory if it doesn’t already exist -n Assigns whatever group is in default Syntax: useradd -d /home/ -m -n

Question 75

Deletes a user account

Answer 75

userdel Options: -r (Recursively) Removes the home directory for specified user Syntax: userdel -r

Question 76

Enables a user to change their password (no user name) or for root to set and modify password settings.

Answer 76

passwd Syntax: passwd

Question 77

Contains the system wide environment and startup programs. When a user logs on to a system for the first time and/or does not have a profile, the settings contained in the systems file are used to create the user’s profile.

Answer 77

/etc/profile

Question 78

``` A tilde (~) references paths that start with a user’s home directory. Depending upon the shell and type of login used, users customize their environment by modifying either ~/.bash_profile,~/.bashrc, or ~/.profile. ```

Answer 78

~/.bashrc