intro to linux - for training.odp

8/19/2019 Intro to Linux - for training.odp

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Linux and Shell Programming

- Mohan


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Why this Course?


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• SECTION I Introduction to Linux

•

SECTION II Command line Interface

• SECTION III Shell Basics

• SECTION IV Pies and Commands

•

SECTION V

Cron !o"s

• SECTION VI Linux #ile Tree

Agenda

• SECTION VII Basic $n

•

SECTION VIII %e&ular

• SECTION I' VI Editor

• SECTION ' Scritin&

•

SECTION 'I

$ser (a

• SECTION 'II #ile Secu


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INTRO!CTION TO LIN!"

• SECTION I

+ ,o- Linux came into this -orld.

+ Linux /rchitecture and Common Linu

+ Various Linux 0istri"utions

+ Linux #ile S)stem

+ Boot Process ,ae )ou eer -ond

+ 0isla) (ana&er 4$I


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#o$ did the Linux %ame into this $orld?

LIN$S TO%V/L0S$SIN4 $NI'

#o$ it is maintained no$?

0EVELOPE% CO(($NIT6

(O0E%/TO%S

LIN$S TO%V/L0S

In 177289


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#istory• In 1771; Linus Toralds -rote his o-n OS e• Su"se?uentl) orted for other hard-are latforms9

&a%ts•

Linux is "ased on $NI'9• Linux is (ultiuser9• Linux uses a hierarchical file s)stem -ith to node called root @ / A• /ccess to the OS throu&h the shell• Offers a text "ased command interface


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Linux Ar%hite%ture and Common terminologies

OS /PPLIC/TION >E%NELBOOTLO/0E% 0/E(ON

S,ELL '11 IN0O (/N/4E% #ILES6STE( P/C>/4ESDP/C>/4E (/


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• >ernel Glue between Hardware and applications

• 0istri"ution Collection of software making up a Linux distribu

• Boot loader Program that boots the operating system (GR!" L#

• Serice Programs that run as background processes (httpd" ft

• Shell Command line #nterpreter

• '11 -indo- (ana&er Graphical subsystem for most of the Linux

• #ile s)stem ethod to store and organi)e files (ext*" ext+" ,

• Pac


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Linux istri'utions

0ifferences package management systems" software 1ersions" and fi


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&edora (CentOS, RHEL)• The Linux


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Some ?uestions -orth thin


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• / :ile system storin& and or&aniGin&

•

/ .artition is a lo&ical art of the dis


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Linux &ile System %ontd++Linux 2 /usr/bin

3in 2 C453indows5system*-

http4//www'pathname'com/fhs/pub/fhs2-'*'pdf - Become an Linux E

Linux 2 case2sensiti1e

3in 2 not case2sensiti1e

http://www.pathname.com/fhs/pub/fhs-2.3.pdfhttp://www.pathname.com/fhs/pub/fhs-2.3.pdfhttp://www.pathname.com/fhs/pub/fhs-2.3.pdf


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The ;oot Pro%ess++

• hen the comuter is started; POST @Po-er On Self TestA is run9• BIOS is stored in the %O( chi9•

$sin& the information in "ios


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• The Boot loader is resonsi"le for loadin& the Oeratin& S)stem9

/st Stage < ;IOS)M;R method• Boot loader resides at 1st sector of hard dis< @(B%A• (B% also has the artition ta"le9• Boot loader finds the "oota"le artition and searches 2nd sta&e of "ootloader9

/st Stage < (&I)!(&I method• $E#I #irm-are contains a "oot mana&er -hich has the location of E#I artition9•

Boot loader resides in E#I artition in hard dis


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The ;oot Pro%ess++

+ Besides startin& the s)stem; init is resonsi"le for


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• 4enerall); in a Linux des


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• 7NOM( is the default to disla) mana&er in most of the enironment9

•

$nit); >0E; 'fce are the other des


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INTRO TO LiN!" CLI

• SECTION II


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• 2 a)s 4$I; CLI

•

NO overhead in CLI interface.

• How do you change your username and password in linux?

GI !GNO"#$ % System Preferences AboutMe change passwo

CLI % Open Terminal type ‘passwd’

• How do you enter &' files? How do you rename &' files?• hich is easier for reetitie tas


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Commands 0escrition

cd Chan&e 0irector)

tree 0isla) the 0irectories and files in tree structurepwd 0isla) current -or


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Try it 3oursel:

19 0isla) )our current director)9 Chan&e to the /etc director)9 Chec< )our current directo29 No- chan&e to )our home director) usin& onl) three


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Commands 0escritionle 0isla)s -hat t)e of file

touch Create an emt) file

touch -t Chan&e timestam

rm remoe a file

rm -f force remoe file

rm -rf %ecursie forcecp

(aing $ith :iles

+ #ileD0ir names are case sensitie+ Eer)thin& is a file @directories are secial casesA+ $se –i for interactie otion


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Try it 3oursel:

19 List the files in the D"in director)929 0isla) the t)e of file of /bin/cat; /etc/passwd and /usr/bin/passwd9

39

0o-nload *:229df usin&wget http4//www'farnell'com/datasheets/+7--8

19 0isla) the t)e of file of +7--8'pdf29 %ename +7--8'pdf to datasheet'9pg @use mA939 0isla) the t)e of file of datasheet'9pg

*9 Create a director) 6/touched and enter it9 Create a emt) file today'txt in touched59 Create a file yesterday'txt to match )esterda)s date9:9 Co) yesterday'txt to copy'yesterday'txt

9 Create a director) called 6/testbackup and co) all files from 6/touched into it9=9 Create a su"director) subdir in the director) testbackup79 $se one command to remoe the director) 6/testbackup and all files into it9

19 Create a director) 6/etcbackup and co) all :'conf files from /etc into it9 0id )ousu"directories of /etc .

http://www.farnell.com/datasheets/46220.pdfhttp://www.farnell.com/datasheets/46220.pdfhttp://www.farnell.com/datasheets/46220.pdf


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Commands 0escrition

head -

disla) the first ten lines of a file

Tail - disla) the last ten lines of a filecat 0isla)Dconcatenate

cat > Create a file

tac 0isla) the file reerse @line orderA

more / less disla)in& files that taing $ith :ile %ontents


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S#(LL CONC(PTS And Commands

• SECTION IV

S


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• ar&uments• hite sace remoal @test -ith MechoA•

Sin&le ?uotes dou"le ?uotes @dou"le ?uotes allo- arsin& of aria"les; sin&le

• ‘which’ command -ill search for "inaries in the P/T, enironment aria"le• External or "uiltin commands. @use Mtype’ to chec


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19 ,o- man) ar&uments are in this line @not countin& the command itselfA9

touch


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139 Exlain the difference "et-een the follo-in& commandsF

echo

/bin/echo

1*9 Exlain the difference "et-een the follo-in& commandsF

echo Hello

echo 2n Hello

159 0isla) / B C -ith t-o saces "et-een B and C9

1:9 Comlete the follo-in& command @do not use sacesA to disla) exactl) the

follo-in& oututF

+?+ >@

A8?A+ >-+

19 $se echo to disla) the follo-in& exactl)F

..QQcommands and ar&uments

=5

#ind t-o solutions -ith sin&le ?uotes; t-o -ith dou"le ?uotes and one -ithout ?uo

1=9 $se one echo command to disla) three -ords on three lines9

Try it yoursel:

Sh ll @ i 'l


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• Permanent shell aria"les called Enironment aria"les; often needed ") alica• Shell aria"les can "e created temoraril) li


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19 $se echo to disla) ,ello follo-ed ") )our username9 @use a "ash aria"leA

29 Create a aria"le ans-er -ith a alue of *29

39 Co) the alue of L/N4 to ()L/N49

*9 List all current shell aria"les9

59 List all exorted shell aria"les9

:9 0o the en and set commands disla) )our aria"le .

:9 0estro) )our ans-er aria"le9

9 Create t-o aria"les; and exort one of them9

=9 0isla) the exorted aria"le in an interactie child shell9

79 Create a aria"le; &ie it the alue 0um"; create another aria"le -ith alue decho and the t-o aria"les to echo 0um"ledore9

19 #ind the list of "ac


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• #ind default shell H &re K$SE%N/(EH DetcDass-d• #ind all Shells aaila"le H cat DetcDshells• Chan&e shell H !ust t)e the shell name• Chan&e default shell H csh

i::erent ty.es o: Shell++

%ontrol o.erators


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%ontrol o.erators

Oerator 0escrition Examles

U (ultile commands run se?uentiall) echo ,ello U echo o

%un "inaries in the "ac


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Each ?uestion can "e ans-ered ") one command line

19 hen )ou t)e ass-d; -hich file is executed .

29 hat


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Examle Commands 0escritions

$ arro- Nai&ation Execute the last command

Execute the last command

ec Execute the last command that started -ith Mec

histor) 1 ,istor) of last 1@nA commands9

*11 Executes the *11th @nthA command9

echo ,IST#ILE The commands are stored in 9"ash[histor)

Shell #istory

Try it 3oursel:


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19 Issue the command echo Hi welcome

29 %eeat the reious command usin& onl) t-o characters @there are t-o soluti

39 0isla) the last 5 commands )ou t)ed9

*9 Issue the lon& echo from ?uestion 1 a&ain; usin& the line num"ers )ou receiecommand in ?uestion 39

59 here are these commands stored -hen exitin& the shell .

Try it 3oursel:

&ile 7lo''ing < generating :ile names


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Examles

Y &enerate filenames; matchin& the asteris<to an) com"ination of characters @een noneA9

ls #ileY

. matchin& the ?uestion mar< -ith exactl) one character9 ls file. ls file..

Z \ an) of the characters "et-een Z and the first su"se?uent \ ls fileZ/7\ fileZaG\

&ile 7lo''ing generating :ile names

Try it 3oursel:

19 Create a test director) and enter it929 Create the follo-in& files F fileA fileA8 fileAA file- ,ile- ,ile* file

fileB! filea fileB fileBBB file( file -

Try it 3oursel:


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39 List @-ith lsA all files startin& -ith file

*9 List @-ith lsA all files startin& -ith #ile

59 List @-ith lsA all files startin& -ith file and endin& in a num"er9

:9 List @-ith lsA all files startin& -ith file and endin& -ith a letter

9 List @-ith lsA all files startin& -ith #ile and hain& a di&it as fifth character9

=9 List @-ith lsA all files startin& -ith #ile and hain& a di&it as fifth character and no

79 List @-ith lsA all files startin& -ith a letter and endin& in a num"er9

19 List @-ith lsA all files that hae exactl) fie characters9

119 List @-ith lsA all files that start -ith f or # and end -ith 3 or /9

129 List @-ith lsA all files that start -ith f hae i or % as second character and end in139 List all files that do not start -ith the letter #9

Try it 3oursel:


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PIP(S AN COMMANS

• SECTION V

In.ut)Out.ut Redire%tion


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• Three "asic streams @stream; stream1; stream2A

. )O .

BashStdin@KA

• BStdout

Bash


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• Redire%tion and .i.es ST0O$T @orA ST0E%% of one command to ST0Icommand

• BB a..end aend to the EO#

• stdin &re somethin& @orA &re somethin& K some[file

&ILT(RS


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Examles

cat uttin& stdin on stdout tac sdf9txt cat cat

tee uttin& stdin on t-o stdout cat sdf9txt tee asdf

&re lines matchin& the strin&9 cat sdf9txt &re sac&re lines not matchin& the strin&9 cat sdf9txt &re s

&re i Case insensitie cat sdf9txt &re i s

cut Select columns from files; deendin& on a delimiter cut dF f1;3 DetcDasecho 1F2F3F*F5 cut

translate Translate the characters cat sdf9txt tr e EMcat sdf9txt tr aG /

cat sdf9txt tr aG Mncat sdf9txt tr s M

-c Count lines; -ords; -c l sdf9txt-c --c c


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• -ho -c l• -ho cut d f1 sort• -ho cut d f1 sort uni?• &re "ash DetcDass-d cut dF f1

0escrition Examles

sort Sort in order sort sdf9txt

sort


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19 Put a sorted list of all "ash users in "ashusers9txt9

29 Put a sorted list of all lo&&ed on users in onlineusers9txt9

39 (a


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Commands 0escrition

man (anual a&e of a command

man (anual a&e of a command

man (anual a&e of a commandman –k List all releant commands -ith one line descrition

apropos Same as a"oe

whatis List the commands one line descrition

whereis 0isla)s the manual a&e location

mand& Indexes the manual entries

Tr) it 6ourself #ind -hat is the command to moe a file9 here is the manual located.hich89,el84o to "in dir


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&IL(S(C!RIT39 CRON DO;S

• SECTION I'

!sers and 7rou.s r - x


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+f you don’t ha,e access to a -le then you cant change its permissions

T)e of #ile %e&ular #ile

d 0irector)

lS)m"olic Lin<DetcDmotd

Named Pie

" Bloc< deiceDdeDsda

cCharacter deiceDdeDconsole

s soc


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• $sers and &rous Mls lh Mcut 2d4 2fA /etc/passwd D column

+f you don’t ha,e access to a -le then you cant change its permissions

ch&r K&rounameHKfilenameH Chan&e &rou ch&r

cho-n KusernameH KfilenameH Chan&e O-ner

chmod chmod &r

chmod uxchmod or

chmod a-

TR3 IT 3O!RS(L&


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• 19 /s normal user; create a director) JDermissions9 Create a file o-ned ") )ours• 29 Co) a file o-ned ") root from DetcD to )our ermissions dir; -ho o-ns this file• 39 /s root; create a file in the users JDermissions director)9• *9 /s normal user; loo< at -ho o-ns this file created ") root9• 59 Chan&e the o-nershi of all files in JDermissions to )ourself9• :9 (a


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• crontab $l lists all the scheduled tas


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• Create Mcron director) in home folder9• $se the date command to see the current timin&9• Schedule a ^o" that uts M,i elcome in the file Mhi9txt9 Mhi9txt should "e in the di• Schedule a ^o" to aend date and time eer) minute9


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MISS( ;ASIC !NI" TOOLS

• SECTION VI


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find

locate

date

cal

slee

time

&Gi

Gcat

"Gi and "Gi2

tar

TR3 IT 3O!RS(L&


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19 Exlain the difference "et-een these t-o commands9 This ?uestion is er) im

)ou dont


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:9 T-o commands that do the same thin&F co) Y9odf files to D"ac


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Linux &ile tree

• SECTION III

Linux :ile tree


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• D"in• "in "inaries for all users• s"in "inaries to confi&ure the oeratin& s)stem

• Dli"• D"in and Ds"in often use shared li"rarie• Li"32 and li":*

• Dot• Dot is to store otional soft-are• Emt) at the start

Linux :ile tree < %on:iguration and data dire%tories


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• Detc• Edita"le Text Confi&uration• Contains machinesecific confi&uration files

• D"oot• D"oot director) contains all files needed to "oot the

comuter • 9cf& or 9conf

init9d Start and sto daemons

x11 DetcD'11Dxor&9conf

s


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(emor) 0irectories

Dde oulated -ith files as the


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19 0oes the file D"inDcat exist . hat a"out D"inDdd and D"inDecho9 hat is the t)e of thesefiles .29 hat is the siGe of the Linux


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:9 $se cat to disla) DetcDhosts and DetcDresol9conf9 hat is )our idea a"out the

of these files .

9 /re there an) files in DetcDs

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