the problem

What directory should your app use for storing user data? If running on macOS, you should use:

~/Library/Application Support/<AppName>

If on Windows (at least English Win XP) that should be:

C:\Documents and Settings\<User>\Application Data\Local Settings\<AppAuthor>\<AppName>

or possibly:

C:\Documents and Settings\<User>\Application Data\<AppAuthor>\<AppName>

for roaming profiles but that is another story.

On Linux (and other Unices) the dir, according to the XDG spec, is:

~/.local/share/<AppName>

appdirs to the rescue

This kind of thing is what the appdirs module is for. appdirs will help you choose an appropriate:

• user data dir (user_data_dir)
• user config dir (user_config_dir)
• user cache dir (user_cache_dir)
• site data dir (site_data_dir)
• site config dir (site_config_dir)
• user log dir (user_log_dir)

and also:

• is a single module so other Python packages can include their own private copy
• is slightly opinionated on the directory names used. Look for "OPINION" in documentation and code for when an opinion is being applied.

some example output

On macOS:

>>> from appdirs import *
>>> appname = "SuperApp"
>>> appauthor = "Acme"
>>> user_data_dir(appname, appauthor)
'/Users/trentm/Library/Application Support/SuperApp'
>>> site_data_dir(appname, appauthor)
'/Library/Application Support/SuperApp'
>>> user_cache_dir(appname, appauthor)
'/Users/trentm/Library/Caches/SuperApp'
>>> user_log_dir(appname, appauthor)
'/Users/trentm/Library/Logs/SuperApp'

On Windows 7:

>>> from appdirs import *
>>> appname = "SuperApp"
>>> appauthor = "Acme"
>>> user_data_dir(appname, appauthor)
'C:\\Users\\trentm\\AppData\\Local\\Acme\\SuperApp'
>>> user_data_dir(appname, appauthor, roaming=True)
'C:\\Users\\trentm\\AppData\\Roaming\\Acme\\SuperApp'
>>> user_cache_dir(appname, appauthor)
'C:\\Users\\trentm\\AppData\\Local\\Acme\\SuperApp\\Cache'
>>> user_log_dir(appname, appauthor)
'C:\\Users\\trentm\\AppData\\Local\\Acme\\SuperApp\\Logs'

On Linux:

>>> from appdirs import *
>>> appname = "SuperApp"
>>> appauthor = "Acme"
>>> user_data_dir(appname, appauthor)
'/home/trentm/.local/share/SuperApp
>>> site_data_dir(appname, appauthor)
'/usr/local/share/SuperApp'
>>> site_data_dir(appname, appauthor, multipath=True)
'/usr/local/share/SuperApp:/usr/share/SuperApp'
>>> user_cache_dir(appname, appauthor)
'/home/trentm/.cache/SuperApp'
>>> user_log_dir(appname, appauthor)
'/home/trentm/.cache/SuperApp/log'
>>> user_config_dir(appname)
'/home/trentm/.config/SuperApp'
>>> site_config_dir(appname)
'/etc/xdg/SuperApp'
>>> os.environ['XDG_CONFIG_DIRS'] = '/etc:/usr/local/etc'
>>> site_config_dir(appname, multipath=True)
'/etc/SuperApp:/usr/local/etc/SuperApp'

AppDirs for convenience

>>> from appdirs import AppDirs
>>> dirs = AppDirs("SuperApp", "Acme")
>>> dirs.user_data_dir
'/Users/trentm/Library/Application Support/SuperApp'
>>> dirs.site_data_dir
'/Library/Application Support/SuperApp'
>>> dirs.user_cache_dir
'/Users/trentm/Library/Caches/SuperApp'
>>> dirs.user_log_dir
'/Users/trentm/Library/Logs/SuperApp'

Per-version isolation

If you have multiple versions of your app in use that you want to be able to run side-by-side, then you may want version-isolation for these dirs:

>>> from appdirs import AppDirs
>>> dirs = AppDirs("SuperApp", "Acme", version="1.0")
>>> dirs.user_data_dir
'/Users/trentm/Library/Application Support/SuperApp/1.0'
>>> dirs.site_data_dir
'/Library/Application Support/SuperApp/1.0'
>>> dirs.user_cache_dir
'/Users/trentm/Library/Caches/SuperApp/1.0'
>>> dirs.user_log_dir
'/Users/trentm/Library/Logs/SuperApp/1.0'