Rospy and os.mkdir() issue - unable to create a directory [closed]

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Hi guys!

I have posted on Stackoverflow this question however since it's also ROS-related I've decided to do that here too. My original post is located here.

I have created a dashboard (inheriting from the Dashboard class based on rqt). I have followed the source code from PR2 and COB in order to populate my widget. In addition some of my toolbar entries also open views containing one or multiple widget (subclassing QWidget) of the same type. Each widget is bound to a ROS process that is taken from a configuration loaded on the parameter server. The purpose of the widget is to allow basic control (start,stop) as well as monitoring of the ROS process status (inactive, running, finished, failed). In the image below you can see more or less how things are connected internally:

There are several goals that the launched bash script (in the image noted as Bash (detached)) has to fulfill are as follows:

• Remain alive even when my UI crashes/is closed - in my main scenario all the processes started by my dashboard have to continue running even when the dashboard itself stops working (for whatever reason)
• Launch a ROS node/nodes (using rosrun, roslaunch or rosservice call (with a Trigger-type feedback)) as a background process
• Write the ROS process's PID in a file .proc - this PID is then used by my widget to control and monitor the process (using kill).
• Retrieve the exit code of the spawned ROS process - the exit code is again written to .proc and can be read by my widget

This solution allows me to continuously monitor a ROS process even if my dashboard stops working (breaks down or is stopped intentionally). Both the .bash and .proc files are further used to restore the state of the application upon relaunch. More on this design can be seen here.

Now I'm currently facing a strange problem (as described in the first link in this post) - whenever I call os.mkdir() following doesn't happen:

• no directory is created (even though it doesn't exists) - the path of the directory is correct. I have used my interactive Python interpreter to do that same procedure of creating it and it worked
• no exception is raised - my rospy.logerr() or rospy.loginfo() seem to be unable to display any exception (if such is raised in this case at all).

Here is the code that I use to create the directory:

def checkRootDirExists(self):
    '''
    Check if the process folder is present and create it if not
    '''
    if not exists(self.dir_name): # Using os.path.exists()
      rospy.loginfo('SR2: Process directory "%s" doesn\'t exist and therefore will be created', (self.dir_name+'/'))
      try:
        mkdir(self.dir_name)
      except OSError as e:
        if e.errno != errno.EEXIST:
          rospy.logerr('Directory exists')
        elif e.errno != errno.EACCES:
          rospy.logerr('Access violation')
        else:
          rospy.logerr('Something else happened')
    else:
      rospy.loginfo('SR2: Process directory "%s" already exists', (self.dir_name+'/'))

I have tried simply using except ... (more)