python open does not create file if it doesnt exist

Posted by Toddeman on Stack Overflow See other posts from Stack Overflow or by Toddeman
Published on 2010-06-03T15:05:54Z Indexed on 2010/06/03 15:14 UTC
Read the original article Hit count: 190

Filed under:

python

|

file-io

I am using Python.

What is the best way to open a file in rw if it exists, or if it does not, then create it and open it in rw? From what i read, file = open('myfile.dat', 'rw') should do this, no? it is not working for me (python 2.6.2) and im wondering if it is a version problem, or not supposed to work like that or what.

The bottom line is, i just need a solution for the problem. I am curious about the other stuff, but all i need is a nice way to do the opening part.

thanks in advance

© Stack Overflow or respective owner

Related posts about python

unmet dependencies in Ubuntu 12.04

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I tried today to install a dvb-card on my Ubuntu 12.04 (Linux blauhai-linux 3.2.0-25-generic #40-Ubuntu SMP Wed May 23 20:30:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux ). The installation failed with an error. After that, i tried to install python (it was already installed but i got this error): linux:~$… >>> More
How can I get sikuli-ide to work?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I installed sikuli-ide with sudo apt-get install sikuli-ide Everything was fine until I tried to start it from the terminal. I typed sikuli-ide But the only response I got was [info] locale: en_US The application was not started, furthermore there is no desktop file and sikuli-ide does not… >>> More
Getting PATH right for python after MacPorts install

as seen on Super User - Search for 'Super User'
I can't import some python libraries (PIL, psycopg2) that I just installed with MacPorts. I looked through these forums, and tried to adjust my PATH variable in $HOME/.bash_profile in order to fix this but it did not work. I added the location of PIL and psycopg2 to PATH. I know that Terminal is… >>> More
call python with system() in R to run a python script emulating the python console

as seen on Stack Overflow - Search for 'Stack Overflow'
I want to pass a chunk of Python code to Python in R with something like system('python ...'), and I'm wondering if there is an easy way to emulate the python console in this case. For example, suppose the code is "print 'hello world'", how can I get the output like this in R? >>> print… >>> More
Python - Calling a non python program from python?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am currently struggling to call a non python program from a python script. I have a ~1000 files that when passed through this C++ program will generate ~1000 outputs. Each output file must have a distinct name. The command I wish to run is of the form: program_name -input -output -o1 -o2… >>> More

Related posts about file-io

File io error Python

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a program that monitors a folder with word documents for any modifications made on the files. The error -Windows Error[2] The system cannot find the file specified- comes when I run the program, open a .doc within the folder make some changes and save it. Any suggestions on how to fix this… >>> More
Problem with File IO and splitting strings with Environment.NewLine in VB.Net

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I was experimenting with basic VB.Net file read/write and encountered this problem. I don't know whether it has something to do with the File IO or the String splitting. I am writing text to a file like so Dim sWriter As New StreamWriter("Data.txt") sWriter.WriteLine("FirstItem") sWriter.WriteLine("SecondItem") sWriter… >>> More
C# Multithreading File IO (Reading)

as seen on Stack Overflow - Search for 'Stack Overflow'
We have a situation where our application needs to process a series of files and rather than perform this function synchronously, we would like to employ multi-threading to have the workload split amongst different threads. Each item of work is: 1. Open a file for read only 2. Process the data in… >>> More
ASP.Net Application Trust Medium File IO Outside Virtual Directory

as seen on Stack Overflow - Search for 'Stack Overflow'
I am trying to determine how suicidal this is... I have a hosting environment where a custom ASP.Net CMS application needs to access the files in the root folder of a website even though it is in a virtual folder so it can be shared accross many sites. I can modify the Medium trust on the server… >>> More
On MacOSX, in a C++ program, what guarantees can I have on file IO

as seen on Stack Overflow - Search for 'Stack Overflow'
I am on MacOSX. I am writing a multi threaded program. One thread does logging. The non-logging threads may crash at any time. What conventions should I adopt in the logger / what guarantees can I have? I would prefer a solution where even if I crash during part of a write, previous writes still… >>> More