How to write a bash script like the python? Lloyd Huang. KaLUG - Kaohsiung Linux User Group COSCUP Aug

Transcription

1 How to write a bash script like the python? Lloyd Huang KaLUG - Kaohsiung Linux User Group COSCUP Aug

2 Before the start Before the start About Bash Python and me. The ipython and lpython.py. A trick, but it touches my heart. Examples of lpython.py : cat /etc/passwd lpython.py \ 'for i in stdin:\n s=i.split(":"); print s[0],s[5],s[6],' uname -a lpython.py 'print stdin.read().split()[0:3]' 2

3 Bash: Questions and answers Bash: Questions and answers Q: How to be more logic and reuse? A: Function. Q: How to do unit testing? A: Function. Q: How different is between Bash function and Python module? A:... 3

4 Bash source VS Python import Bash source VS Python import Python A module allows you to logically organize your Python code. Grouping related code into a module makes the code easier to understand and use. Python modules are easy to create; they're just files of Python program code. if name == ' main ': 4

5 Bash source VS Python import How Bash do it? 5

6 Bash source VS Python import #!/bin/bash #!/usr/bin/python funtest() { def funtest(): echo "" print "" } funfake() { def funfake(): echo "func for fake" print "func for fake" } # main if name == ' main ': funtest funtest() funfake funfake() $> source samp00.sh $> python >>> import samp00 func for fake $> bash samp00.sh $> python samp00.py func for fake func for fake 6

7 Bash source VS Python import #!/bin/bash #!/usr/bin/python funtest() { def funtest(): echo "" print "" } funfake() { def funfake(): echo "func for fake" print "func for fake" } return 2> /dev/null if name == ' main ': funtest funtest() funfake funfake() $> source samp00.sh $> python >>> import samp00 $> bash samp00.sh $> python samp00.py func for fake func for fake 7

8 Bash source VS Python import #!/bin/bash funtest() { echo "" } funfake() { echo "func for fake" } if [ "$0" == "$BASH_SOURCE" ]; then funtest funfake fi 8

9 From xkcd

10 Python module and docstring Python module and docstring import, from import module as someone Import module del Delete object docstring Python Documentation Strings 10

11 Python module and docstring #!/usr/bin/python def funtest(): """ Here is python docstring for funtest. Here is python docstring for funtest. """ print "" def funfake(): "Here is python docstring for funcfake." print "func for fake" if name == ' main ': funtest() funfake() 11

12 Python module and docstring $> python >>> import samp02 >>> samp02. samp02. doc ( samp02.funtest( samp02.funfake( >>> samp02.funtest() >>> help (samp02.funtest) >>> Help on function funtest in module samp02: funtest() Here is python docstring for funtest. Here is python docstring for funtest. 12

13 Python module and docstring >>> samp02.funfake. doc 'Here is python docstring for funcfake.' >>> print samp02.funfake. doc Here is python docstring for funcfake. >>> import samp02 as new_samp02 >>> new_samp02.funtest() >>> del new_samp02 >>> new_samp02.funtest() Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'new_samp' is not defined 13

14 Bash import and docstring? Bash import and docstring? Usage: source import.sh import, from import module as someone Import module del module Delete module help module.function Documentation Strings 14

15 Bash import and docstring? #!/bin/bash funtest() { doc =" Here is bash import.sh docstring for funtest Here is bash import.sh docstring for funtest " echo "" } funfake() { doc ="Here is bash import.sh docstring for funfake" echo "func for fake" } if [ "$0" == "$BASH_SOURCE" ]; then funtest funfake fi 15

16 Bash import and docstring? $> source import.sh $> import samp02.sh $> samp02 samp02.funfake samp02.funtest $> samp02.funtest $> import samp02.sh as new_samp $> new_samp.funtest $> help new_samp.funtest Here is bash import.sh docstring for funtest Here is bash import.sh docstring for funtest $> del new_samp $> new_samp.funtest bash: new_samp.funtest command not found 16

17 uid, gid = split(``1000:100'',``:'')? uid, gid = split(``1000:100'',``:'')? Python : split name, passwd, uid, gid, note, homedir, shell = string.split("www-data:x:33:33:www-data:/var/www:/bin/sh",":") Bash : read LDread () { doc ="LDread '.' 'V KH ' c1 c2 c3 c4 c5 c6 c7" } local ifs con ifs="$1"; shift con="$1"; shift IFS="$ifs" read $@ < <(echo $con) 17

18 阿 宅 圖 片 來 源 : 公 立 怪 咖 國 民 小 學

19 Hook Hook #!/bin/bash funtest() { doc ="Hook test - Part I PreHook=\"echo This is PreHook\" PostHook=\"echo This is PostHook\"" } test -n "$PreHook" && $PreHook echo "" test -n "$PostHook" && $PostHook 19

20 Hook $> import hook00.sh $> hook00.funtest $> help hook00.funtest Hook test - Part I PreHook="echo This is PreHook" PostHook="echo This is PostHook" $> PreHook="echo This is PreHook" $> PostHook="echo This is PostHook" $> hook00.funtest This is PreHook This is PostHook 20

21 Hook #!/bin/bash funtestprehook () { return } funtestposthook () { return } funtest() { doc ="Hook test - Part II funtestprehook () { echo \"This is funtestprehook\"; } funtestposthook () { echo \"This is funtestposthook\"; } " } funtestprehook echo "" funtestposthook 21

22 Hook $> import hook01.sh $> hook01.funtest $> help hook01.funtest Hook test - Part II hook01.funtestprehook () { echo "This is funtestprehook"; } hook01.funtestposthook () { echo "This is funtestposthook"; } $> hook01.funtestprehook () { echo "This is funtestprehook"; } $> hook01.funtestposthook () { echo "This is funtestposthook"; } $> hook01.funtest This is funtestprehook This is funtestposthook 22

23 Demo Demo 23

24 Advantages VS Problems Advantages VS Problems Advantages Function reuse Unit testing Name space Documentation strings Grouping up commands Problems To Conflict with ImageMagick Can't work with busybox ash 24