When i try and use either mp3write~ or oggwrite~ in a patch to create a file neither appears able to create a file.
Take the attached patch as an example. If i use the "open /track.mp3" it fails, if i use "open /tmp/track.mp3" the console claims the file is created but when you run the start, stop the file is not created. I have tried this on osx 10.8 and 10.9.

It must be something i am missing here because i cant find any bug reports of this.

Help appreciated.

Have

http://www.pdpatchrepo.info/hurleur/bug_demo.pd

works for me on 10.9, have you checked if the file exists? I think open is only for writing.
to check if the file exists: put

test ! -e /tmp/track.mp3; echo $?

in terminal. if it exists then you'll get a 1 and if not a 0. you could also just do

ls /tmp

to see what's going on

btw it probably fails when you try to create on your volume because you don't have permission to write there. also I think you forgot to attach the patch
/tmp is hidden by default on osx, you can change it so all hidden files are shown, or chflags /tmp to be nohidden

Right I am slightly confused lots going on there.

First i have permission on the volume assuming it is saving into the /tmp folder in the project directory which I created and is not saving into some hidden folder on mac osx.

the "open" message when used with sfwrite~ (eg "open /track.wav") creates the file in the current directory. Should i be expecting the same behaviour with mp3 and oggwrite? Or do these two expect there to be an audio file present already.

I did forget to attach sorry, I always do that. Should be there now but it isnt anything special just a silly demo.

firstly, in unix and maybe posix any pathname starting with / means relative to the root directory, or Macintosh HD. You are looking for the behavior of just starting with a name, like tmp/track.mp3

secondly not all objects reference the directory of the patch but the directory that pure data is running in, which I believe is the root directory = Macintosh HD = /. I actually filed a bug report for this exact reason by mistake with msgfile. Basically you need to provide absolute pathnames and can't write in certain directories. It has to do with which c function the programmer of the external used to write files
so you were using /tmp, which is a hidden folder in OSX. there's probably a really long mp3 there now !-)

to get the current directory of your patch you can use ggee/getdir

Sir you are a Gentlemen,

Bang on, /tmp folder full of random empty audio files.
Patch is running in project directory however to open file needed an absolute path name which looked like /Users/me/Desktop/project/file.

I had actually tired lots of these however i was using ~ for home which clearly it didn't recognise.

You have also helped me solve a multi-platform problem by introducing me to getdir

Thanks Man