Curs 3Shell scripting. Automatizare

Gestiunea Serviciilor de Ret,ea

20 octombrie 2011

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Moto

Anything worth doing once is worth automating.

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Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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Prerequisites

I “Cartea de USO”:http://books.google.com/books?id=_JFGzyRxQGcC

I Capitolul 12 – Shell scripting

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Suport

I “Unix and Linux System Administration”I Chapter 2 – Scripting and the Shell (pg. 29-53, pg. 73-76)I Chapter 9 – Periodic Processes

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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Shell

I interpretor de comenzi

I /bin/bash, /bin/sh, /bin/dash, /bin/tcsh

I operatori shell

I redirectare

I ınlant,uirea comenzilor

I programare

I variabile

I comenzi de tip instruct, iuni (if, for, while)

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Funct, ionare shell

bash

fork

bash

exec

ls

wait

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Comenzi interne s, i comenzi externe

I built-in commandsI pwd, cd, exit, set, ulimit, exec, source, ., :I help source

I comenzi externeI ls, chmod, adduser, ifconfig, lsmodI man adduser, info ls

I type

razvan@valhalla:~$ type lsmod

lsmod is /bin/lsmod

razvan@valhalla:~$ type source

source is a shell builtin

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Tipuri de utilizare a Bash

I interactivI neinteractiv

I bash test.shI bash -c “ls”

I shell de loginI /etc/profile, ∼/.bash profile, ∼/.bash login, ∼/.profile,∼/.bash logout

I shell non-loginI ∼/.bashrc (pentru shell interactiv)

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Operatori shell

I secvent, iereI &&, ;, ||, &

I redirectareI >, <, 2>, 2>&1, &>, >>, <<

I ınlant,uire comenziI |I <(command)

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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Script shell

I comenzi s, i operatori shell

I automatizare

I ıncepe, de obicei, cu #!/bin/bashI rulare

I bash hello.bashI chmod a+x hello.bash && ./hello.bash

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Script shell (2)

razvan@valhalla:~/curs-05$ cat hello.bash

#!/bin/bash

echo "Hello, World"

exit 0

razvan@valhalla:~/curs-05$ bash hello.bash

Hello, World

razvan@valhalla:~/curs-05$ chmod a+x hello.bash

razvan@valhalla:~/curs-05$ ./hello.bash

Hello, World

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Cum arata, ın general, un shell script?

I o ınlant,uire de comenzi

I nu apar for, while, until, case – doar pentru cazuri speciale

I variabile, expandare de comenzi, opt, iuni utile

I filtre de text, prelucrare de text

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Cand/De ce shell scripting?

I automatizare + lene

I doua sau mai multe comenzi frecvente secvent, iale

I hook-uri, conectarea de alte act, iuni

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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Shell programming

I variabileI a=5

I fara spat, ii

I echo $a

I Ce este o variabila de mediu?I o variabila mos, tenita de procesele copilI demo

I construct, ii de ciclare s, i decizieI for, while, if, case, select

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Shell programming (2)

for i in list; do command_list; done

for i in 1 2 3 4 5 6 7 8 9 10; do echo $i; done

for i in $(seq 1 10); do echo $i; done

for ((i = 1; i <=10; i++); do echo $i; done

for i in {1..10}; do echo $i; done (bash-only)

command | while read a b c; do command_list; done

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Shell programming (3)

if command; then command_list; fi

if test $# -eq 0; then command_list; fi

test -f file

test -d directory

test string1 == string2

test num1 -lt num2

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Caractere speciale shell

I $ – shell expansion

I ;, |, & – ınlant,uirea comenzilor

I ”, ’, \ – escaping

I *, [, {, ? – globbing

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Argumente script shell

I $#I numarul total de argumentI argc

I $0I numele scriptului/executabilului

I $1, $2, $3, $4 ...I argumentele scriptului

I $*, $@I lista de argumente a scriptului

I shiftI shiftarea argumentelor unui scriptI poate primi ca argument valorea shift-ului

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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Filtre de text

I ın Unix fis, ierele sunt textI de configurareI jurnaleI ies, irile comenzilor

I Do one thing do one thing well!I fiecare comanda prelucreaza textul s, i este transmis altei

comenziI operatorul |

I I’m lovin’ this!

last -30 | head -n -2 | cut -d ’ ’ -f 1 | sort | uniq | wc -l

2

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head, tail, cat, tac

I catI atent, ie la crearea unui nou procesI cat file.txt | grep pattern → grep pattern <

file.txt

I head -n -10I toate liniile mai put, in ultimele 10

I tail -n +11I toate liniile ıncepand de la linia 11

I tail este util pentru log-uri (tail -f)

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grep

I nu as,aI cat file.txt | grep patternI grep razvan /etc/passwdI grep /home/razvan /etc/passwd – cand e folosit?I grep -r function /path/to/source/folderI dpkg -l | grep libapache2-mod-php5

I atent, ie la escaping (pipe, star, plus)

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cut, tr, wc

I cutI doar cand e simpluI cut -d ’:’ -f 1 /etc/passwdI pentru “extra features” – awk

I trI what does this button do?

I tr -d -c ’A-Za-z’ < /dev/urandom | head -c 8

I pentru “extra features” – sed

I wcI word countI -c, -l, -w

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diff

I diferent,ele ıntre doua fis, iere

I folosit pentru crearea de patch-uri

razvan@valhalla:~$ diff test.sh test2.sh

6c6

< bibi

---

> more is less

I ce trebuie scos (<), ce trebuie introdus (>)

I comanda patch aplica un patch obt, inut cu diff (sau git diff

sau svn diff)

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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find

I cautare ın sistemul de fis, iere

I find . -name ’*.c’

I find -type f -name ’*.c’

I find -type f -name ’*.c’ -perm /111

I find -type f -name ’*.c’ -perm /111 -exec chmod

a-x {}I find -mindepth 1 -maxdepth 1

I for file in $(find ...); do ... done

I a=(*); for file in ${a[@]}; do ... doneI NU for i in *I NU for i in $(ls ...)

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xargs

I trimite liniile de la intrarea standard ca argumente comenziiprimite ca argument

I find . -type f | xargs rm -f

I find . -type f | xargs -I {} cp {} /tmp

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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Globbing

I filename expansion

I diferit de setul standard de expresii regulateI *

I orice caracter de oricate ori

I ?I orice caracter

I [abc]I set de caracter

I [ˆabc]I diferit de setul de caractere

I {jpg,png,bmp}I select, ie

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Expresii regulate

I x*I caracterul x de oricate ori (posibil niciodata)

I x+I caracterul x de oricate ori (cel put, in o data)

I x?I caracterul x cel mult o data

I . (punct)I orice caracter

I ˆI ınceput de rand

I $I sfars, it de rand

I [a-z]I set de caractere

I [ˆa-z]I set complementar de caractere

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sed

I opt, iuni multipleI de obicei folosit la substitut, ia s, irurilor

/pattern/s/to_be_replaced/to_replace/options

sed ’/\/home\//s/^\([^:]\+\):/\1_rules:/’ < /etc/passwd

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awk

I Advanced cut

I Permite formarea unui separator pe baza unei expresii regulate

I Limbaj de programare

cut -d ’:’ -f 1

awk -F ’:’ ’{print $1;}’

awk -F ’[ \t]+’ ’/ana/ {print $3;}’

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Exemple

1 /^$/d

2 s/a/b/g

3 s/^a/b/g

4 s/\<ana\>/bogdan/g

5 s/[ \t]\+\<ana\>$/b/g

6 s/^|type.*//g7 s/\([^ \t,]\+\),\([^ \t,]\+\)/\2 | \1/8 s/[ \t]*<li>\(.*\)<\/li>/* \1/g9 s/<\/pre>/<\/code>/g

10 s/\[\(http[^]]\+\)]/[[\1]]/g11 s/\xc5\x9f/\xc8\x99/g

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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cron

I serviciu de planificare a unei sarcini

I planificare la nivel de secunda

I planificare statica sau periodica

I /etc/init.d/cron

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Configurare cron

I la nivel de sistem

I /etc/crontab

I /etc/cron.allow

I /etc/cron.deny

I la nivelul utilizatorului

I crontab -l (listare)

I crontab -e (editare)

I /var/spool/cron/crontabsI format

I minute, hour, day of month, month, day of week, command0 */8 * * * /home/razvan/cron/rsync_backup_mamba

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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Cuvinte cheie

I shell

I comenzi interne, externe

I operatori shell

I shell script

I redirectare

I secvent, iere

I variabile

I if, for, case, while

I shell expansion

I caractere speciale

I escaping

I globbing

I expresii regulate

I filtre de text

I head, tail, cat, tac

I grep, awk, sed

I cut, tr, wc

I cron

I crontab

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Resurse utile

I http://www.gnu.org/software/bash/manual/bashref.html

I http://www.tldp.org/LDP/abs/

I http://www.shelldorado.com/

I http://mywiki.wooledge.org/BashFAQ

I #bash pe Freenode (IRC)

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Outline

Interact, iunea cu shell-ul

Shell scripting

Shell programming

Filtre de text

find

Globbing s, i expresii regulate

cron

Keywords

Intrebari

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