The beauty of Python: Some examples with os and sys modules - part 2

Today i will tell about sys and os modules.
The module os has OS routines for Mac, NT, or Posix depending on what system we're on.
The module sys provides access to some objects used or maintained by the interpreter and to functions that interact strongly with the interpreter.

Some useful functions with sys module.

>>> print sys.version
2.5.2 (r252:60911, Oct  5 2008, 19:24:49) 
[GCC 4.3.2]
>>> print sys.version_info
(2, 5, 2, 'final', 0)
>>> print sys.subversion
('CPython', 'tags/r252', '60911')
>>> print sys.platform 
linux2
>>> print sys.ps1
>>> 
>>> print sys.ps2
... 
>>> print sys.prefix
/usr
>>> print sys.path
['', '/usr/lib/python2.5', '/usr/lib/python2.5/plat-linux2', '/usr/lib/python2.5/lib-tk',
'/usr/lib/python2.5/lib-dynload', '/usr/local/lib/python2.5/site-packages',
 '/usr/lib/python2.5/site-packages', '/usr/lib/python2.5/site-packages/Numeric',
'/usr/lib/python2.5/site-packages/PIL', '/usr/lib/python2.5/site-packages/gst-0.10',
 '/var/lib/python-support/python2.5', '/usr/lib/python2.5/site-packages/gtk-2.0', 
'/var/lib/python-support/python2.5/gtk-2.0']
>>> print sys.modules.keys()
['apt.os', 'email.iterators', 'apport.sys', 'random', 'apport.atexit', 'subprocess',
 'email.MIMEImage', 'gc', 'apport.pwd', 'os.path', 'encodings.encodings', 'email.mime',
 'email.MIMEText', 'xml', 'email.time', 'struct', 'tempfile', 'base64', 'apt.cache',
 'pyexpat.errors', 'apt_pkg', 'apport', 'email.binascii', 'email.Parser', 'zipimport',
 'apport.xml', 'xml.dom.copy', 'encodings.utf_8', 'apt.apt_pkg', 'email.quoprimime',
 'email.mime.text', 'email.urllib', 'email.FeedParser', 'signal', 'email.encoders',
 'pyexpat.model', 'apport.packaging_impl', 'apport.cStringIO', 'quopri',
 'email.Message', 'cStringIO', 'zlib', 'locale', 'email.charset', 'apport.fileutils',
 'xml.parsers.expat', 'atexit', 'email.quopriMIME', 'encodings', 'email.Generator',
 'apport.warnings', 'apport.problem_report', 'apt.fcntl', 'email.MIMEAudio', 'urllib',
 're', 'apt.select', 'email.quopri', 'apport.report', 'email.mime.base', 'email.errors',
 'email', 'math', 'fcntl', 'apport.os', 'apt.progress', 'UserDict', 'exceptions',
 'apport.grp', 'apport.shutil', 'codecs', 'xml.dom.domreg', 'email.Header', '_locale',
 'email.Iterators', 'socket', 'thread', 'traceback', 'apt.apt', 'e,
 'SUDO_COMMAND': '/bin/su', 'SUDO_GID': '999', 'SDL_VIDEO_CENTERED': '1',
 'PWD': '/home/mint/Desktop', 'COLORTERM': 'gnome-terminal', 'MAIL': '/var/mail/root'}
mail.Charset', 'xml.dom.xmlbuilder', 'os', 'marshal', 'apport.stat', 'apport.re',
 'apt.gettext', 'email.uu', '_sre', 'unittest', '__builtin__', 'apport.apport',
 'xml.parsers', 'apport.fnmatch', 'apport.urllib', 'operator', 'xml.parsers.pyexpat',
 'email.Errors', 'select', 'apt.string', 'apport.glob', 'apt.warnings', 'email.socket',
 'posixpath', 'email.base64MIME', 'errno', '_socket', 'binascii', 'email.Utils',
 'sre_constants', 'email.MIMEMessage', 'email._parseaddr', 'email.sys',
 'apport.traceback', 'apt.package', 'apt.random', 'xml.dom.NodeFilter',
 'email.MIMENonMultipart', '_codecs', 'apport.unittest', 'apport.apt', 'email.os',
 'email.utils', 'pwd', 'apport.time', 'copy', '_struct', '_types', 'email.email',
 'apt.cdrom', 'uu', 'xml.dom.minidom', 'apport_python_hook', 'apt', 'email.random',
 'posix', 'encodings.aliases', 'apt.sys', 'fnmatch', 'sre_parse', 'pickle', 'copy_reg',
 'sre_compile', '_random', 'site', 'email.base64', 'apt.errno', '__main__', 'problem_report',
 'pyexpat', 'email.MIMEBase', 'email.message', 'string', 'email.mime.nonmultipart',
 'apport.subprocess', 'shutil', 'strop', 'grp', 'encodings.codecs', 'gettext',
 'email.warnings', 'xml.dom.minicompat', 'email.MIMEMultipart', 'types', 'apport.tempfile',
 'stat', '_ssl', 'warnings', 'encodings.types', 'glob', 'email.re', 'sys', 'email.Encoders',
 'readline', 'email.cStringIO', 'xml.dom', 'xml.dom.xml', 'apport.signal', 'sitecustomize',
 'email.mime.email', 'email.base64mime', 'email.mime.multipart', 'apport.packaging',
 'urlparse', 'linecache', 'email.string', 'apt.re', 'time', 'gzip']

And now, some useful functions with os module.

>>> print os.uname()
('Linux', 'mint', '2.6.27-7-generic', '#1 SMP Fri Oct 24 06:42:44 UTC 2008', 'i686')
>>> print os.ttyname(1)
/dev/pts/0
>>> print os.times()
(0.050000000000000003, 0.02, 0.0, 0.0, 17186002.649999999)
>>> print os.environ
{'USERNAME': 'root', 'LANG': 'en_US.UTF-8', 'TERM': 'xterm', 'SHELL': '/bin/bash',
 'XDG_SESSION_COOKIE': '842d38513df1a6bb7490c8a14bf69489-1274456064.963733-1686354756',
 'SUDO_COMMAND': '/bin/su', 'SHLVL': '1', 'RUNNING_UNDER_GDM': 'yes', 'SUDO_UID': '999',
 'SUDO_GID': '999', 'PWD': '/home/mint/Desktop', 'LOGNAME': 'root', 'USER': 'root',
 'COLORTERM': 'gnome-terminal',
 'PATH': '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games',
 'MAIL': '/var/mail/root', 'SUDO_USER': 'mint', 'HOME': '/root', 'DISPLAY': ':0.0',
 '_': '/usr/bin/python', 'XAUTHORITY': '/home/mint/.Xauthority'}
>>> print os.mkdir('aaa')
None
>>> print os.mkdir('aaa')
Traceback (most recent call last):
File "", line 1, in 
OSError: [Errno 17] File exists: 'aaa'
>>> print os.listdir('/')
['media', 'root', 'sbin', 'usr', 'lib', 'tmp', 'home', 'var', 'cdrom', 'etc',
 'rofs', 'bin', 'boot', 'dev', 'initrd.img', 'mnt', 'opt', 'proc', 'srv',
 'sys', 'vmlinuz']

These is just a brief tutorial about sys and os modules.

The beauty of Python: Simple functions - part 1

Validation of a condition and return result in 'Yes' or 'No'.

>>> def valid(x,y):
...     return ('Yes' if x==y else 'No') 
... 
>>> valid(2,3)
'No'
>>> valid(2,2)
'Yes'

Some usefull functions from string module .

>>> import string 
>>> var_template_string=string.Template(" The $subj $vb $something")
>>> var_template_string.substitute(subj="PC", vb="working", something="now")
' The PC working now'
>>> some_string_dictionary={'subj':'car', 'vb':'is', 'something':'blue'}
>>> var_template_string.substitute(some_string_dictionary)
' The car is blue'
>>> some_string_dictionary

Some example with re module and html tag

>>> import re
>>> t='<p>'
>>> some_tag = re.compile(r'<(.*?)(\s|>)')
>>> m = some_tag.match(t)
>>> print m
<_sre.SRE_Match object at 0xb7f79da0>
>>> dir(m)
['__copy__', '__deepcopy__', 'end', 'expand', 'group', 'groupdict', 'groups', 'span', 'start']
>>> print m.start()
0
>>> print m.groups()
('p', '>')
>>> print m.group()
<p>
>>> print m.span()
(0, 3)

The re module has many usefull functions.
This is just some examples to show the simplicity of python language.

Python and OpenGL - first steps

First you need to install python .
Second you need to install pyopengl module.
This is easy if we use some linux distributions.
On Fedora we can use command yum.
On Debian and Ubuntu we can use apt-get.
At last we need some basicaly examples.
We can get some examples from:PyOpenGL-Demo
But this is not all we will need more.
To go on next step we will need to read OpenGL specifications.
Try to use search on internet to see more about OpenGL.