= Python =
Python is a programming language that lets you work more quickly and integrate your systems more effectively.
Links:
* [[http://docs.python.org/2/library/]]
* [[http://www.tutorialspoint.com/python/]]
== UTF-8 ==
At the start of source code files:
{{{#!highlight python
# -*- coding: utf-8 -*-
print u"Olá mundo" # hello world in portuguese
}}}
Letter '''á''' is encoded as hexadecimal '''0xC3A1''' in UTF-8 and as '''0x00E1''' in UTF-16.
[[http://www.fileformat.info/info/unicode/char/e1/index.htm]]
Letter '''ú''' is encoded as hexadecimal '''0xC3BA''' in UTF-8, as '''0x00FA''' in UTF-16 and as '''0xFA''' in latin-1/ISO8859-1/CP-1252.
{{{#!highlight python
#utf-8 data
utf81 ='\xc3\xba'
# convert from utf-8 to unicode
unic = utf81.decode('utf-8')
for c in unic:
print '%04X'%(ord(c))
# convert from unicode to latin1/ISO8859-1 CP-1252
lat1=unic.encode('latin1')
for c in lat1:
print '%02X'%(ord(c))
}}}
== Utf-8 and Unicode ==
{{{#!highlight python
utf81='\xe1\xb7\x97' #utf-8 data
unic = utf81.decode('utf-8') #converts from utf-8 to unicode (utf-16)
for c in unic:
print '%04X'%(ord(c))
type(unic) # unicode, 2 bytes per char
type(utf81) # str, 1 bytes per char
}}}
== Time and date ==
{{{#!highlight python
import time
# get seconds since epoch until now in UTC to a string year-month-dayThour:minute:second
strutc = time.strftime('%Y-%m-%dT%H:%M:%S', time.gmtime() )
# get seconds since epoch until now in localtime to a string year-month-dayThour:minute:second
strlocal = time.strftime('%Y-%m-%dT%H:%M:%S', time.localtime() )
# number seconds since epoch
nrSeconds = time.mktime(time.gmtime())
nrSeconds = time.time() #usually is UTC on all OS
# from timestamp to string date
import datetime
print(datetime.datetime.fromtimestamp(1284101485).strftime('%Y-%m-%d %H:%M:%S'))
#
def toUTCDateStr(timestamp):
return datetime.datetime.utcfromtimestamp( timestamp ).strftime('%Y-%m-%d %H:%M:%S ')
# timedelta
import datetime
x=datetime.datetime.fromtimestamp(1284101485)
nowx=datetime.datetime.now()
ts=(nowx-x).total_seconds()
print int(ts)
}}}
== Write and reading data for a plist file ==
A plist file stores data in XML format.
{{{#!highlight python
import plistlib
value = [{'key1':123,'key2':'asdf'},{'keyx1':'testing','keyz1':'yup'}]
# save value in plist file
plistlib.writePlist(value,'/tmp/plist1.plist')
o=plistlib.readPlist('/tmp/plist1.plist')
print o
}}}
Content of the file '''/tmp/plist1.plist'''
{{{#!highlight xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
<dict>
<key>key1</key>
<integer>123</integer>
<key>key2</key>
<string>asdf</string>
</dict>
<dict>
<key>keyx1</key>
<string>testing</string>
<key>keyz1</key>
<string>yup</string>
</dict>
</array>
</plist>
}}}
== Threading ==
{{{#!highlight python
#!/usr/bin/python
# timestable.py
# calculates the times table in concurrency
import threading
import time
class TimesTable (threading.Thread):
def __init__(self, timesTable):
threading.Thread.__init__(self) #required
self.timeTable = timesTable
self.count = 1
def run(self):
loop=True
while loop:
time.sleep(1) #sleep for 1 second
result=self.timeTable * self.count
print "%d*%d=%d"%(self.timeTable,self.count,result)
if self.count<10:
self.count = self.count+1
else:
self.count=1
# create threads
timesTable2 = TimesTable(2)
timesTable5 = TimesTable(7)
# start the threads
timesTable2.start()
timesTable5.start()
}}}
== unit tests ==
{{{#!highlight python
import unittest
class SimpleWidgetTestCase(unittest.TestCase):
def setUp(self):
self.widget = Widget('The widget')
def tearDown(self):
self.widget.dispose()
self.widget = None
}}}
== cython ==
Installation:
* su
* cd /tmp
* wget http://cython.org/release/Cython-0.19.1.tar.gz
* tar xvzf Cython-0.19.1.tar.gz
* cd Cython-0.19.1
* python setup.py build
* python setup.py install
== pymssql ==
Requires cython.
Installation:
* su
* cd /tmp
* wget [[http://pymssql.googlecode.com/files/pymssql-2.0.0b1-dev-20111019.tar.gz]]
* tar xvvzf pymssql-2.0.0b1-dev-20111019.tar.gz
* cd pymssql-2.0.0b1-dev-20111019
* python setup.py build
* python setup.py install
* python
* import pymssql
== pywhois ==
Python module for retrieving WHOIS information of domains [[http://code.google.com/p/pywhois/]].
Fetch code with mercurial:
* cd /tmp
* hg clone https://code.google.com/p/pywhois/
* cd pywhois
* python setup.py build
* python setup.py install
== Syntax highlighting on Vim for wsgi ==
Edit ~./.vimrc:
{{{#!highlight bash
syntax on
filetype on
au BufNewFile,BufRead *.wsgi set filetype=python
}}}
== Get file modification time ==
{{{#!highlight python
import os
nrSeconds=os.path.getmtime('/folder/file') # unix epoch, nr secs since 1970-01-01 00:00:00
}}}
== Kill process with PID ==
{{{#!highlight python
import os
import signal
os.kill(pid,signal.SIGTERM)
}}}
== Log message to /var/log/messages or /var/log/syslog ==
{{{#!highlight python
import syslog
syslog.syslog(syslog.LOG_INFO,'message to syslog')
}}}
== Simple process monitor ==
{{{#!highlight python
# example service, dummyService.py
import time
while True:
try:
f=open('filex.log','wb')
f.write('%f'%(time.time()))
f.close()
time.sleep(5)
except KeyboardInterrupt:
quit()
}}}
{{{#!highlight python
#service monitor.py
# * * * * * /usr/bin/python /home/vitor/svc/monitor.py
import os
import syslog
import subprocess
if __name__=="__main__":
files = os.listdir('/proc')
script="dummyService.py"
prefix="dummyService:"
svcRunning=False
for file in files:
if file.isdigit():
cmdline = open('/proc/%s/cmdline'%(file),'r').read()
proc = "%s %s "%(file,cmdline)
if script in proc :
svcRunning=True
if svcRunning==False:
syslog.syslog(syslog.LOG_INFO,'%s process created '%(prefix) )
subprocess.Popen(['/usr/bin/python','dummyService.py'],cwd='/home/userx/svc')
}}}