How to change the working directory for a shell script

Quick and dirty:

In your start up script instead of just executing the python script, use cd first.

#!/bin/sh

cd /home/username/projectname &&
python ./scriptname.py

There are a couple of ways around this directly in your Python script.

If your script is always going to be in "/home/username/projectname/subfolder", you can simply add that to your search path inside Python:
```
import sys
sys.path.append("/home/username/projectname/subfolder")
```
I suspect, however, that you might have this in multiple "projectname" directories, so a more generic solution is something like this:
```
import sys
import os
sys.path.append(os.path.join(os.path.dirname(sys.argv[0]), "subfolder"))
```
This finds the directory where the Python script is (in sys.argv[0]), extracts the directory part, appends "subfolder" onto it, and puts it into the search path.

Note that some operating systems may only give the executable name in sys.argv[0]. I don't have a good solution for this case, perhaps someone else does. You may also need to inject a os.path.abspath() call in there if sys.argv[0] has a relative path, but play around with it a bit and you should be able to get it working.
Similar to the above answer, you can have the Python script change directories all by itself with no need for a wrapper script:
```
import os
os.chdir("/home/username/projectname")
```

An even faster, dirtier way of doing it (with a subshell):

$ ( cd my/path/to/folder && python myprogram.py )

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