Develop Reference

Putting something on your system path

I am trying a python, django tutorial. It says type django-admin.py however I get 'command not found' with this.
Someone told me that the problem could be that django is not in your system path, what does that mean?
I am using ubuntu.

System path is an system environment variable that contains the path for some folders where the os will search for applications, scripts, etc.
In windows django-admin.py is in C:\Python\scripts, so if you have set the PYTHONPATH environment variable and added all the required python folder in that variable like C:\Python;C:\Python\Lib;C:\Python\scripts;C:\Python\Lib\site-packages, the os will automatically find django-admin.py when you will type the command django-admin.py startproject myproj on commandline.
same with linux, the django-admin.py is in /usr/bin/django-admin.py if you install django for the default python installation.
so, one way could be if you create a alias for that script so that you can run it from where ever you want.
i am using centos and what i did is i edited the /etc/bashrc and added
alias djangoadmin='/usr/bin/django-admin.py' and it works for me very well.

On Linux, check this official doc page: Link
On Windows, this one should do want you want: Link

If you installed Django from the Ubuntu repositories via apt-get or synaptic, the script will be simply django-admin (without the .py).

Getting PyDev to recognize the correct Python Interpreter on Eclipse under OS X Lion

I have two versions of python installed on my mac running OSX Lion. The first is the default python version that ships with OSX and is found in /usr/bin/python. The version I want to use is the version I downloaded from python.org, and that is installed in /Library/Frameworks/Python.framework/Versions/2.7/bin/python. I want to use Eclipse and PyDev using the python.org version as the interpreter. So, in Eclipse, I go to preferences and set the version installed in /Library/Frameworks/Python.framework/Versions/2.7/bin/python to be the interpreter.
in a terminal window, if I type:
$ which python
I get "/Library/Frameworks/Python.framework/Versions/2.7/bin/python" because I set my $PATH accordingly (modified .bash_profile to permanently do so)
but if I run the following simple script in Eclipse:
import os
os.system("which python")
the script's output is "/usr/bin/python"
Things I have tried as suggested by other similar posts:
tried removing and re-adding the interpreter location
tried adding the /Library/.../package-sites to PYTHONPATH
Why isn't eclipse using the interpreter I explicitly tell it to use? Any help with this issue will be greatly appreciated!

The problem is that os.system('which python') will search for the python in the path, not the one where you're currently running (so, its output is correct).
What you want to use/check instead is sys.executable (this attribute will point to your currently running executable).
As for the wxPython issue, which error are you having? (probably another question in stackoverflow thought).

I think Eclipse is running the correct python. In your code when running under eclipse which python does not find the python running. Try
import sys
print sys.version
The issue here is that running a GUI app from the desktop/dock/folder does not load your .bash_profile and so which python does not find your change to the PATH. To change your path for GUI apps you need to edit ~/.MacOSX/environment.plist

I agree with Mark here. sys.version will be what eclipse uses to run your code. os.system("which python") will be python found in PATH that eclipse forwarded when running your code. Perhaps if you use PATH tweaks you should set environment variables for running code in Eclipse too.

How to import modules from alternate locations when using Python IDLE?

I've been trying to figure this out for more than 2 days, screening the internet and the tutorial, but yet I don't have solved my problem. I'm a real newb and don't yet really know what I'm doing..
Software I use:
Mac OS X 10.6
Python v3.2.2
Interactive interpreter (IDLE)
Problem:
IDLE's default directory is /Users/ME/Documents/. Files with the extention .py can only be opened when located in this directory. However, I made a folder where I would like to save all the .py files etc that have to do with this software. Currently, IDLE cannot load .py files from the chosen directory by me.
What I did first was I added to IDLE:
import sys.
sys.path.append('Users/Mydir/')
sys.path
However, in an already existing thread from 2010 I read sys.path is for the Interpreter ONLY, and that if I am to change this I need to modify the PYTHONPATH environment variable:
PYTHONPATH="/Me/Documents/mydir:$PYTHONPATH"
export PYTHONPATH
However, I'm confused how to use this and cannot find answers to my following questions:
1) PYTHONPATH (.py?) is already existing on my computer when I installed the program?
If YES, where is it? I cannot find it anywhere.
If NO, I need to create one. But where and what should be the content so that IDLE can load files from a non-default directory? Should it contain only the words in bold?
I hope I made my problem clear.
Cheers

It's not totally clear to me what you mean by load. That could mean Open and Close files in the IDLE editor. Or it could mean being able to use the Python import statement to load existing Python modules from other files. I'll assume the latter, that by load you mean import.
There are two general ways to launch IDLE on Mac OS X. One is from the command line of a terminal session; if you installed Python 3.2 using the python.org installers, by default typing /usr/local/bin/idle3.2 will work. The other way is by launching IDLE.app from /Applications/Python 3.2, i.e. by double-clicking its icon. Because you say the default directory for files is your Documents folder, I'm assuming you are using the second method because IDLE.app sets Documents as its current working directory, which becomes the default directory for *Open*s and *Save*s and is automatically added as the first directory on Python's sys.path, the list of directories that Python uses to search for modules when importing.
If you want to add other directories to sys.path, as you've noted you can use the PYTHONPATH environment variable to do so. The standard way to do this is to add an export PYTHONPATH=... definition to a shell startup script, like .bash_profile. However, if you use IDLE.app, no shell is involved so commands in .bash_profile have no effect.
While there are ways to modify the environment variables for OS X GUI apps, in this case, a simpler solution is to use the other method to invoke IDLE, from the command line of a shell session, using either /usr/local/bin/idle3.2 or, if you've run the Update Shell Profile command in the /Applications/Python 3.2 folder (and opened a new terminal session), just idle3. Then, a PYTHONPATH environment variable you set up will be inherited by that IDLE.
BTW, there is no direct way to modify the initial current working directory of IDLE.app from Documents other than modifying the code in IDLE. If you start IDLE from a command
line, it inherits the current working directory of the shell.
[UPDATE] But rather than fooling around with defining PYTHONPATH, here is another even simpler, and probably better, approach that should work with either IDLE.app or the command line idle. It takes advantage of Python path configuration (.pth) files and user site-package directories. Assuming you are using a standard Python framework build of 3.2 (like from a python.org installer) on Mac OS X, create a path file for the directory you want to permanently add to sys.path. In a terminal session:
mkdir -p ~/Library/Python/3.2/lib/python/site-packages
cd ~/Library/Python/3.2/lib/python/site-packages
cat >my_paths.pth <<EOF
/Users/YOUR_USER_NAME/path/to/your_additional_python_directory_1
/Users/YOUR_USER_NAME/path/to/your_additional_python_directory_2
EOF
Now, whenever you run that Python 3.2 or IDLE under your user name, the directories you have added to the .pth file will automatically be added to sys.path.
BTW, the exact path location of the user site-packages directory for versions of Python earlier than 3.2 or 2.7 may be slightly different. Also, on other Unix-y systems, the default location for the user site-package directory is ~/.local/lib/python3.2/site-packages.

PYTHONPATH is an environment variable (see here and here). I don't have a Mac, but from the threads I have linked to you would type something like
launchctl setenv PYTHONPATH=/Me/Documents/mydir:$PYTHONPATH
on the command line to allow you to run Python scripts from /Me/Documents/mydir. Alternatively, put this line in a file called .bashrc in your home directory (~) and this path will be set each time each time you open a terminal. See here for a short introduction to .bashrc and other .bash* files. Hope that helps.
EDIT See also this question.

Python 3.2 doesn't work with python 2.7

I already have python 2.7 (installed using activepython). I'm trying to use python 3.2 just to learn more about it so i downloaded it from python.org
python 2.7 still works perfectly, but python 3.2 gives me this error when i try to open the ide.
and then I see the send error window, if i install python 3.2 using activepython i see the same error.
I'm using windows xp pro sp3 32 bit and i had the same error on sp2... How do I fix it?
EDIT #Zuljin
This is the first time that i use dependancy walker so could you give me a hand please
this is what i see
what does that mean? I already have these files...

I saw a lot of answers here. But, I think the file that you are trying to run is not correct
C:\Python32\Pythonw.exe
is not the one you use to open idle.
Open
C:\Python32\Lib\idlelib\idle.pyw

Python 2.x and 3.x can cohabitate perfectly in win xp and win 7, either 32 or 64 bits.
If you first installed the ActiveState Python distribution, be careful when installing python-3.2.2.msi.
When you arrive to the customize python 3.2.2 screen, (un)check 'register extensions' to make the feature unavailable (that is: do not register extensions).
I have installed this way both distributions in different computers without any problem so far.
Note: Check your environment variables. Only python 2.7 should be in the path (if you installed before the two distros you could have them both in the path. Remove python 3.2 path)
Edit:
From Ankit post I realized that in fact you were trying to open IDLE, maybe.
If you follow my installation instructions when you call idle.bat from the py3.2 idlelib folder you actually get idle for python 2.7 as this is what the call find in the windows path. To be able to open idle for py3.2 in the presence of python 2.7 as the registered python, I use a .bat file modified from that in the distribution:
idle_stay.bat
#echo off
rem Working IDLE bat for Windows - Custom bat for py3k as secundary python
C:\Python32\pythonw C:\Python32\Lib\idlelib\idle.pyw %1 %2 %3 %4 %5 %6 %7 %8 %9
The name idle_stay.bat is because I put this file in the folder where the official idle.bat is (C:\Python32\Lib\idlelib\idle_stay.bat). In this way it does not get overwritten each time I unisntall and reinstall a new version of python 3

It seems to me you have associated a *.py or *.pyw file extension type to some version of python.exe and/or pythonw.exe you aren't clear about. This is often, but not exclusively done from within Microsoft's "explore.exe" File Manager (I believe in Options).
I disagree that this is a reliable method:
C:\Python32\Lib\idlelib\idle.pyw
as this method will run whichever program is assigned to the "pyw" extension. That could be:
C:\Python32\pythonw.exe
or
C:\Python26\python.exe
or whatever might have happened to your file extension association as per OS or bad PATH environment variable setting. It is better to do something like this:
C:\Python32\pythonw.exe C:\Python32\Lib\idlelib\idle.pyw
where you are explicidly telling the OS to run the python executable from a specific path and selecting a specific python script in the file/folder hiearchy.
Another thing you can try to gather info is just:
python.exe -V
which will tell you the version number.
Another thing you can do:
Open a DOS command prompt and type:
set PATH=C:\Windows;C:\Windows\system32;C:\Python32
python.exe and note the version and whether is runs.
exit()
exit
Once working debug your PATH. You can use this Python script to gather intel.
If you turned off your WinXP findfile stuff (like I have) you can use this script:
inpath.py can help shed some light.
Run this python script like this:
Drop to a DOS prompt
cd to your folder with a working python.exe version.
and type python.exe inpath.py python*
where inpath is in that same folder for this test/debug.
inpath.py will search your path for all files associated as "runable" in your OS and that is in your "PATH" with the python*.* pattern.

How to integrate Django and Cygwin?

I have a Windows box with cygwin, python and django installed.
Now I want to run django-admin, but when I do I get the error:
$ django-admin.py
c:\Python26\python.exe: can't open file '/usr/bin/django-admin.py': [Errno 2] No such file or directory

From here
For Windows users, who do not have symlinking functionality available, you can copy django-admin.py to a location on your existing path or edit the PATH settings (under Settings - Control Panel - System - Advanced - Environment...) to point to its installed location.
hope this helps

I just ran into the exact same problem. I've found that if you already have the windows version of python installed, it seems to get priority over the cygwin version. I solved the problem by editing /etc/profile and changed:
PATH=/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:$PATH
...to:
PATH=/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:
...which I think stops cygwin from adding the normal windows path. Once you've got that working, download django into some directory, move into that directory and type:
python setup.py install
I was having problems to begin with because I had omitted the 'python' bit at the start

As for the step on how to start your django in cygwin
first open your windows command prompt
then register the python environment by doing this:
Path %path%;C:\Python27;C:\Python27\Scripts
then now go to the installation folder of your cygwin
cd C:\cygwin
then run the cygwin.bat like this:
C:\cygwin>cygwin.bat <enter>
then cygwin will open, and type python to see if it now working
$ python
Voila we are done!

Sort of sounds like the windows version of Python is trying to run instead of the cygwin one. What happens if you type this:
$ python django-admin.py
Here I'm assuming
$ which python
Finds the cygwin version of python (which will be something like /usr/bin/python).
You may also try (temporarily) uninstalling the windows version of python and use only cygwin.

Help us help you. Is there a reason why you are running the windows python interpreter (c:\Python26\python.exe) as oppose to the cygwin python interpreter (/usr/bin/python.exe)? That could be your problem. So to troubleshoot that, you might consider removing the windows native interpreter or simply making sure the cygwin path is listed before the c:\Python26 path in the windows global PATH variable.

Add the location of your django/bin folder (or wherever else you keep django-admin.py) to your PYTHONPATH environment variable.

Like Brian mentioned you are running the Windows version of Python which won't work with the Cygwin installation.
A word of warning. When I first started using Django, I tried installing it in Cygwin and had a variety of problems and ended up switching to the regular Windows version of Python. Unfortunately, I didn't document all my issues, but I remember some of them had to do with the database libraries. Anyway, that was a few months ago when I knew less about Django than I do now. Maybe the problems I ran into have been solved and perhaps now that I know more I could get it to work, but running Django on Cygwin does seem to be the road less traveled. Good luck. :)

Just copy the django-admin.py to the current location you are working on for e.g
on Cygwin:
<root>/projects/
on your windows directory it will look like this:
C:\cygwin\home\<your computer name>\projects\
once you copy the file, you can create your project by typing this command:
$ python django-admin.py startproject mysite
and that's all - you have completed your first project using the Cygwin linux-like environment.

Add two lines to .bash_profile and .bashrc files (view their difference here). You can find them in C:\cygwin\home\[username]:
export PATH=$PATH:/cygdrive/c/python2.7
export PYTHONPATH=$PYTHONPATH:/cygdrive/c/python2.7/Lib/site-packages
Hope this helps