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os.system argument from config file

I made this activity and it works. I need to have config file with USB/VID/PID.
def resetactivity():
os.system(r'"devcon.exe restart "*USB\VID_04E8&PID_3321*"')
I try to do this with config parser. I made config.txt:
[My Section]
usbdev = r'"devcon.exe restart "*USB\VID_04E8&PID_3321*"'
I read my config file in Python:
config = configparser.ConfigParser()
config.read('config.txt')
usbdev = config.get('My Section', 'usbdev')
And when I am trying to use this in os.system command like this:
def resetactivity():
os.system(usbdev)
I get this result:
The filename, directory name, or volume label syntax is incorrect.
'PID_3321*"'' is not recognized as an internal or external command,
operable program or batch file.

Try this code
import configparser
import os
def resetactivity():
config = configparser.ConfigParser()
config.read('config.txt')
usbdev = config.get('My Section', 'usbdev')
print(usbdev)
os.system(usbdev)
if __name__ == "__main__":
resetactivity()
With config.txt formatted as
[My Section]
usbdev = devcon.exe restart "USB\VID_04E8&PID_3321"

Updating of a config file written in python

I'm writing a simulation software which should support reading parameters from a config file or from the command line. It is very important to be able to track what was the configuration of a simulation, I'm committing the config file to a local git repository at the start of simulation.
Now if I have parameters on the command line they have higher priority than the ones in the config file. But I also want to commit them. I guess I could save the python objects of a configured simulation, just before it is started. But it would be more elegant, if I could just update the config file with the command line parameters before committing it.
The reason I write the config file in python is that I have to define some python objects in it. I have something like
import SomeSimulationClass
SIMULATOR = SomeSimulationClass
in my config file and the SIMULATOR can then be swapped easily.
If I want to use something like configparser I can't have objects I believe.
Is there any easy way to update a python config file? All variable names in it are already defined, I just want to change the values. The only thing I can think of is parsing the file, comparing strings between the file and the command line parameters ...

You can write whatever you want into a file, and then later, Configparser can read
from it using values from your variables. Here is an example on how I used Configparser to read environment from config file.
import os
from ConfigParser import SafeConfigParser
conf_filename = os.getenv("CONFIG_FILE")
src_dir = os.getenv("CONFIG_DIR")
conf_file = os.path.join(src_dir,conf_filename)
parser = SafeConfigParser()
parser.read(conf_file)
section = env
server = parser.get(section, 'host')
db_port = parser.get(section, 'db_port')
ws_port = parser.get(section, 'ws_port')
and the config file itself:
[PROD]
host=xxx-yyy-15
db_port=1521
ws_port=8280
ora_server=xxx-xxx-xxx.com
sid=XXXXX
userid=xxxx
passwd=xxxx
[STAGE]
host=xxx-yyy-04
db_port=1521
ws_port=8280
ora_server=yyy-yyy-yyy.com
sid=YYYYYY
userid=yyyy
passwd=yyyy

I found a way to do what I want. Some small modifications were necessary to my python config module to allow it to be rewritten with the following script, but it works for my purposes:
with open('merged_config.py', 'w') as merged_config, \
open(base_config_module.__file__, 'r') as base_config:
for line in base_config:
if 'import' in line:
# copy imports from bas config
merged_config.write(line)
for item in dir(base_config_module):
if item.startswith("__"):
# ignore __variables like '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__' ...
continue
if item == 'SimulationSteps':
# ingoring my imports
continue
item_val = getattr(base_config_module, item)
# I had to overwrite the __repr__() method of Enums which I used. Everyting else worked fine.
merged_config.write('%s = %s\n' % (item, repr(item_val)))

How to pass user_data script to Python Openstack Heat-API client

How to pass user_data script to Python Heat-API client.
I have the following script in a file I want to pass into an instance as user_data during creating, but I am not sure
how to go about it doing. I am using the Heat API to create the instance. The below code creates the stack with the heat template file with no user_data.
Any pointers would be appreciated.
env.yml
user_data:
#!/bin/bash
rpm install -y git vim
template_file = 'heattemplate.yaml'
template = open(template_file, 'r')
stack = heat.stacks.create(stack_name='Tutorial', template=template.read(), parameters={})

On your yaml Heat template, you should add:
parameters:
install_command:
type: string
description: Command to run from user_data
default: #!/bin/bash rpm install -y git vim
...
myserver:
type: OS::Nova::Server
properties:
...
user_data_format: RAW
user_data: { get_param: install_command }
And pass the new parameter through parameters = {}, from your create line on Python:
heat.stacks.create(stack_name='Tutorial', template=template.read(),
parameters={ 'install_command': '...' })

Create Ipython magic command for saving last console input to file

Remark now I found a solution of doing it. I want to implement my own magic command in ipython which saves the last input to a python file in order to produce executable python code interactively:
I thought about saving it as own magicfile.py in the ipython startup directory:
#Save this file in the ipython profile startup directory which can be found via:
#import IPython
#IPython.utils.path.locate_profile()
from IPython.core.magic import (Magics, magics_class, line_magic,
cell_magic, line_cell_magic)
# The class MUST call this class decorator at creation time
#magics_class
class MyMagics(Magics):
#line_magic
def s(self, line):
import os
import datetime
today = datetime.date.today()
get_ipython().magic('%history -l 1 -t -f history.txt /')
with open('history.txt', 'r') as history:
lastinput = history.readline()
with open('ilog_'+str(today)+'.py', 'a') as log:
log.write(lastinput)
os.remove('history.txt')
print 'Successfully logged to ilog_'+str(today)+'.py!'
# In order to actually use these magics, you must register them with a
# running IPython. This code must be placed in a file that is loaded once
# IPython is up and running:
ip = get_ipython()
# You can register the class itself without instantiating it. IPython will
# call the default constructor on it.
ip.register_magics(MyMagics)
So right now i type in a command in ipython, then s; and it appends it to the logfile of today.

Use the append argument, -a, with %save.
If this is the line you wish to save:
In [10]: print 'airspeed velocity of an unladen swallow: '
Then save it like this:
In [11]: %save -a IPy_session.py 10
The following commands were written to file `IPy_session.py`:
print 'airspeed velocity of an unladen swallow: '
See the Ipython %save documentation

It works by using the IPython Magic history. In the history the old inputs are saved and you just pick the last one and append it to a file with the date of today, so that you can save all inputs from one day in one log-file. The important lines are
get_ipython().magic('%history -l 1 -t -f history.txt /')
with open('history.txt', 'r') as history:
lastinput = history.readline()
with open('ilog_'+str(today)+'.py', 'a') as log:
log.write(lastinput)
os.remove('history.txt')

How do I get Plone to read my pythonrc?

I am using the collective.python buildout.
I have the following .pythonrc (configured with export PYTHONSTARTUP=~/.pythonrc):
import readline
import rlcompleter
readline.parse_and_bind('tab: complete')
When I run Python in the shell, tab completion works. When I run Plone in debug mode it does not. Unless, I paste the contents of my .pythonrc into the Plone debug Python prompt. What am I missing here?
Note: Pasting the contents of my .pythonrc only works when I install Plone via python bootstrap.py (i.e. bootstrapping Plone buildout with collective.python Python). If I install Plone inside a virtualenv, nothing works. But at least in that scenario, the missing functionality makes sense to me (i.e. something is probably missing from the virtualenv that is required to make tab completion work.)

The instance controller uses two command-line switches; -i for interactive mode, and -c to load the Zope configuration and set up the app variable. The -c switch is what disables the PYTHONSTARTUP environment variable.
You could modify the plone.recipe.zope2instance package to run the script anyway.
In plone.recipe.zope2instance, find the plone/recipe/zope2instance/ctl.py file, alter the do_debug() method to:
def do_debug(self, arg):
interactive_startup = ("import os;"
"os.path.exists(os.environ.get('PYTHONSTARTUP', '')) "
"and execfile(os.environ['PYTHONSTARTUP']); del os;"
'import Zope2; app=Zope2.app()')
cmdline = self.get_startup_cmd(self.options.python,
interactive_startup,
pyflags = '-i', )
In fact, I like the idea of supporting PYTHONSTARTUP so much I committed that change to the recipe already, see rev 536f8fc1c4!

I do import user. This reads ~/.pythonrc.py. Note the .py extension. I have set that file as my PYTHONSTARTUP
I'll paste that file for good measure. I have cobbled it together a few years ago. Not sure if it is still the best, as I see comments about 2006 and python2.3. It does the trick though.
$ cat ~/.pythonrc.py
# See http://blog.partecs.com/2006/02/27/source-inspector/
#import pydoc
import inspect
import rlcompleter, readline
readline.parse_and_bind('tab: complete')
# def source(obj):
# """source of the obj."""
# try:
# pydoc.pipepager(inspect.getsource(obj), 'less')
# except IOError:
# pass
# From /usr/local/lib/python2.3/user.py
import os
home = os.curdir # Default
if 'HOME' in os.environ:
home = os.environ['HOME']
elif os.name == 'posix':
home = os.path.expanduser("~/")
# Make sure home always ends with a directory separator:
home = os.path.realpath(home) + os.sep
# From http://wiki.python.org/moin/PdbRcIdea
# Command line history:
histfile = home + '.pyhist'
try:
readline.read_history_file(histfile)
except IOError:
pass
import atexit
atexit.register(readline.write_history_file, histfile)
readline.set_history_length(200)
# Cleanup namespace
# del atexit
# del home
# del histfile
# del os
# del readline
# del rlcompleter