introduction to bash scripting greek

7/23/2019 Introduction to Bash Scripting GREEK

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Bash Scripting

( e p a r a s k e i @ c s d . a u t h . g r )

( )

5

, 2 0 2 0 1 5
mailto:[email protected]:[email protected]


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/ :

script

/

(Functions)

: If-Else

:

: Tips,

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/ 1960 (command-line interfaces)

Unix Bourne Shell(sh)

o Bourne Shell , scripts

shells : C shell (csh), Korn shell (ksh), Bourne-Again shell (bash)

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/ Bash Bourne Shell, Unix-based

Linux :

GUI: , drop-down menus,

Terminal: (terminal)

terminal Bash -

Bash scripting

.sh

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script terminal - , , :

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script II, / / terminal

.sh

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script script files bash interpreter

, /bin/bash

# , , ,

interpreter

: interpreter!

script,

terminal

chmod 700 /path/to/script/file.sh

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script IV

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script V /path/to/script/file.sh

./script.sh

, , script

, cd (change directory) path (.)

, cd directory script

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script VI

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/ , bash /

echo,

, readread name

echo $name

,

inlineread p Type in your name : name

echo $name

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bash scripting , ,

,

= whitespace!

var=FOO

, $

echo $var

/ _ !

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,

$HOME:

$BASH: Bash

$HISTFILE:

$USER: bash

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bash scripts

$?: (return value, exit status)

$#: script

$0, $1, $2, ...: script $@: script

$$: pid script

$SECONDS: script

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- (child process) (parent process)

C/C++/... main()

bash-script exit

0

lefteris@ubuntu:~/Desktop$ ls

Project1 script_examples script.sh~ vmware-tools-distrib

lefteris@ubuntu:~/Desktop$ echo $?

0

lefteris@ubuntu:~/Desktop$ ls /test

ls: cannot access Desktop/test: No such file or directory

lefteris@ubuntu:~/Desktop$ echo $?

2

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Script:#!/bin/bash

echo Number of parameters: $#

echo First parameter: $1

echo Third parameter: $3

echo All parameters: $@

:

lefteris@ubuntu:~$ ./test.sh hello world

Number of parameters: 2First parameter: hello

Third parameter:

All parameters: hello world

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C, myfunction(){ ... }

!

scripts (non-interactive) (interactive)

set

lefteris@ubuntu:~$ testfunction(){

echo Hello World!

echo Input arguments: $@ }

lefteris@ubuntu:~$ testfunction Hello Again!

Hello World!

Input arguments: Hello Again!

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return exit code

Bash

!

( )

local

local ,

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script#!/bin/bash

myfunc1(){echo Start of function 1

echo Hello World!

echo End of function 1

}

myfunc2(){echo Start of function 2

myfunc1

echo End of function 2

}

echo Start of script

myfunc1

myfunc2

echo End of script

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lefteris@ubuntu:~$ ./test.shStart of script

Start of function 1

Hello World!

End of function 1

Start of function 2

Start of function 1

Hello World!

End of function 1End of function 2

End of script

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If-Else I !

if [ condition1 ]; thenaction1

elif [ condition2 ]; thenaction2

elseaction

fi

; then

;

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If-Else IIlefteris@ubuntu:/home$ x=1lefteris@ubuntu:/home$>if [ $x == 1 ]; then> echo x is 1>else> echo x is not 1>fix is 1

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If-Else III (Test

[

) bash [ .

if bash

[ 0 then

[ test

if

[

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If-Else IVlefteris@ubuntu:/home$ x=1lefteris@ubuntu:/home$ test $x == 1lefteris@ubuntu:/home$ echo $?0lefteris@Ubuntu:/home$ [ $x == 1 ]

lefteris@ubuntu:/home$ echo $?0lefteris@ubuntu:/home$ test $x == 2lefteris@ubuntu:/home$ echo $?1lefteris@ubuntu:/home$>if test $x==1; then> echo x is 1>fix is 1

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(while)while [ condition ]do

actiondone :

lefteris@ubuntu:/home$ unset INPUTlefteris@ubuntu:/home$ while [ $INPUT != bye ];> do read INPUT; echo $INPUT;> donetesttest

byebyelefteris@ubuntu:/home$

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(for) foreach for

for variableName in { list };

do

actiondone

seq built-in range

for count in {1..10} for count in seq 1 10

do

echo $count

done

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(for)$ seq 1 41234$ for count in seq 1 4; do echo $count; done1234

$ for count in seq 1 4; do echo $count; doneseq14

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IV (for)lefteris@ubuntu:/home$ for file in ls; do echo $file; donelost+foundlefteris

` ( ~ ) (command

substitution) $(ls)

.

lefteris@ubuntu:/home$ lslost+found lefterislefteris@ubuntu:/home$ ls

lost+found: command not foundlefteris@ubuntu:/home$ echo ls lost+found lefteris

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case $variable in

pattern-1)commands;;

pattern-2)

commands;;

pattern-3|pattern-4|pattern-5)commands;;

*)

commands;;esac *) default case

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echo Which Linux distribution do you know? read DISTRcase $DISTR in

ubuntu)echo I also know it!;;

centos|rhel)echo Hey! It is my favorite Server OS!;;

windows)echo Very funny...;;

*)

echo Hmm, seems Ive never used it.;;

esac

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Bash (Bourne Shell)

: !

!

.

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whatis:

man: manual (vim-styleshortcuts! :q )

whereis: path , manual

which: path

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lefteris@ubuntu:~/Desktop$ whatis lsls (1) - list directory contentslefteris@ubuntu:~/Desktop$ whereis lsls: /bin/ls /usr/share/man/man1/ls.1.gzlefteris@ubuntu:~/Desktop$ which ls/bin/ls

lefteris@ubuntu:~/Desktop$ whatis timetime (1) - run programs and summarize systemresource usagetime (2) - get time in secondstime (7) - overview of time and timerslefteris@ubuntu:~/Desktop$ whereis timetime: /usr/bin/time /usr/bin/X11/time /usr/include/time.h

/usr/share/man/man1/time.1.gz /usr/share/man/man7/time.7.gz

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/

$mv src dest

( src) dest

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file file2

$cp file file2

file folder file2

$cp file folder/file2

fold1 fold2

$cp fold2/* fold1

fold1 fold2

$cp -R fold2/* fold1

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file ( )

$touch file

folder

$mkdir folder

file

$rm file

folder

$rm -R folder folder

$rmdir folder

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I / .

group (. chown chgrp)

: , group

: ,

lefteris@ubuntu:~/Desktop/project1$ ls -l proj* data*

-rw-rw-r-- 1 lefteris lefteris 12307 Oct 17 13:44 data.out-rwxrwxr-x 1 lefteris lefteris 3789 Oct 17 13:15 project1.sh

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// / file$chmod +x file$chmod +r file$chmod +w file // / file$chmod -x file$chmod -r file$chmod -w file / file / group / other /

$chmod u+r file$chmod g+r file$chmod o+r file$chmod a+r file

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. chmod 774 file , group,

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# Permission rwx

7 read, write and execute 111

6 read and write 110

5 read and execute 101

4 read only 100

3 write and execute 011

2 write only 010

1 execute only 001

0 none 000


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(stdin, cout)

ls > output

(stderr, cerr)

ls > output 2>errors

ls > output 2&>1

. (append) >>

ls >> output

ls -la >> output

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cat < input

cat ( )

lefteris@ubuntu:~/Desktop/project1$ cat

Hello World!

Hello World!

Test

Test

^C

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cat (catenate)

cat file1 file2

cat file1 file2 > file3

, ( less)

cat file1

Bonus: sortsort unsorted_file > sorted_file man sort !!!

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Pipelining , pipeline |

myfile

cat myfile | sort

ls | sort

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Io bash

$ echo $((5 + 1))

6$a=1;b=3$ result=$((5 + $a * $b))$ echo $result8

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bc (bench calculator)

$ a=2; b=3.141;

$(echo $a * $b | bc)$ echo $result6.282$ echo $(echo 5 * $b | bc)15.705

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grep Io grep (Global Regular Expression Print)

file test

grep file testcat file | grep test

cat file | grep -n test

cat file | grep -v test

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grep II

cat file | grep -c test

case-insensitive

cat file | grep -i test !

.

c*

c\+

[0 - 9] ( 0 9)

^c

$

^

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awk I textprocessing

.

(default: /tab)

awk .

condition { action }

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awk II

awk { print } < data

awk { print $2,$5 } < data

!

-Fawk < /etc/passwd -F: { print $6 }

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awk III awk ....

lefteris@ubuntu:~$ echo 5 4 | awk { print $1 + $2 }

9

lefteris@ubuntu:~$ echo 5 4 | awk { print $1 $2 }54

lefteris@ubuntu:~$ echo 5 4 | awk { print $1, $2 }

5 4

0

awk $1==0 { print $2 } < data

awk $/regex/ { print $2 } < data

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sleep time: time

wc file: , (word count)

wc -w file: (word count)

head file -n 3:

tail file -n 3:

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background I ,

&

lefteris@ubuntu:~$ gedit

lefteris@ubuntu:~$ gedit &[1] 6428

lefteris@ubuntu:~$ jobs

[1]+ Running gedit &

lefteris@ubuntu:~$ jobs

[1]+ Done gedit

background bash jobnumber pid

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background II wait jobs ( bash)

lefteris@ubuntu:~$ sleep 10 &

[1] 6528lefteris@ubuntu:~$ sleep 15 &[2] 6529lefteris@ubuntu:~$ sleep 5 &[3] 6530lefteris@ubuntu:~$ wait

[1] Done sleep 10[3]+ Done sleep 5[2]+ Done sleep 15

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()

:

SIGINT (interrupt, Ctrl-C): .

( Ctrl-C vim).

SIGTSTP (temporarily stop, Ctrl-Z): (. jobs). jobs .

SIGTERM (termination): SIGINT.

SIGKILL (kill): .

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( );

kill

kill pid SIGTERM ( )

.

kill -9 pid

9 SIGKILL ( )

BONUS: stdin ( sort). EOF (Ctr-D) .

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ps (processes)ps auxps -ef -fps -f -u lefterisps -ef | grep bash

top

procfs ( /proc)

cat /proc/pid/status$ cat /proc/1276/status | grep ThreadsThreads: 3

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Tips

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Tips I () ;

ls > /dev/null

;for word in cat file;do

echo $worddone

;while read line

do echo $worddone < file

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Tips II ;if [ -z $variable ]

if [ x$variable == x ]

;if [ -n $variable ]

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Advanced Bash-Scripting Guide http://tldp.org/LDP/abs/html/index.html

Beginning Linux Programming, Neil Matthew, Richard Stones

http://ubuntuguide.org

man pages
http://tldp.org/LDP/abs/html/index.htmlhttp://tldp.org/LDP/abs/html/index.htmlhttp://ubuntuguide.org/http://ubuntuguide.org/http://ubuntuguide.org/http://ubuntuguide.org/http://tldp.org/LDP/abs/html/index.html

introduction to bash scripting greek

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