How to write a bash script like the python?
Lloyd Huang
KaLUG - Kaohsiung Linux User Group
COSCUP Aug 18 2012
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]'
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: ....
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.
Bash source VS Python import
How Bash do it?
Bash source VS Python import
#!/bin/bash | #!/usr/bin/python funtest() { | def funtest():
echo "func for test" | print "func for test"
} |
funfake() { | def funfake():
echo "func for fake" | print "func for fake"
} |
# main | if __name__ == '__main__':
funtest | funtest()
funfake | funfake()
$> source samp00.sh $> python
func for test >>> import samp00 func for fake
$> bash samp00.sh $> python samp00.py func for test func for test func for fake func for fake
Bash source VS Python import
#!/bin/bash | #!/usr/bin/python funtest() { | def funtest():
echo "func for test" | print "func for test"
} |
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 test func for test func for fake func for fake
Bash source VS Python import
#!/bin/bash
funtest() {
echo "func for test"
}
funfake() {
echo "func for fake"
}
if [ "$0" == "$BASH_SOURCE" ]; then
funtest
funfake
fi
Python module and docstring
Python module and docstring
• import, from
• import module as someone
– Import module
• del
– Delete object
• docstring
Python module and docstring
#!/usr/bin/python
def funtest():
"""
Here is python docstring for funtest.
Here is python docstring for funtest.
"""
print "func for test"
def funfake():
"Here is python docstring for funcfake."
print "func for fake"
if __name__ == '__main__':
funtest()
funfake()
Python module and docstring
$> python
>>> import samp02
>>> samp02.
samp02.__doc__( samp02.funtest( samp02.funfake(
>>> samp02.funtest()
func for test
>>> help (samp02.funtest)
>>>
Help on function funtest in module samp02:
funtest()
Here is python docstring for funtest.
Here is python docstring for funtest.
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()
func for test
>>> del new_samp02
>>> new_samp02.funtest()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'new_samp' is not defined
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
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 "func for test" }
funfake() {
__doc__="Here is bash import.sh docstring for funfake" echo "func for fake"
} if [ "$0" == "$BASH_SOURCE" ]; then funtest funfake fi
15
Bash import and docstring ?
$> source import.sh $> import samp02.sh $> samp02 samp02.funfake samp02.funtest $> samp02.funtestfunc for test
$> import samp02.sh as new_samp $> new_samp.funtest
func for test
$> 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
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 '.' 'V01.01.05.28.KH0.10.28' c1 c2 c3 c4 c5 c6 c7" local ifs con
ifs="$1"; shift con="$1"; shift
IFS="$ifs" read $@ < <(echo $con) }
Hook
Hook
#!/bin/bash
funtest() {
__doc__="Hook test - Part I
PreHook=\"echo This is PreHook\"
PostHook=\"echo This is PostHook\""
test -n "$PreHook" && $PreHook
echo "func for test"
test -n "$PostHook" && $PostHook
}
Hook
$> import hook00.sh
$> hook00.funtest
func for test
$> 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
func for test
This is PostHook
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 "func for test" funtestPostHook }
Hook
$> import hook01.sh $> hook01.funtest func for test
$> 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 func for test
Demo
Demo
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
