2. Configuration
The first program start of QGIS creates (if not available) a user profile in the user's home directory, by default in %APPDATA%\QGIS\QGIS3- The profile (
default) contains subfolders for processing, color palettes, various (optional) templates, GUI adjustments, etc. as well as additional Python plugins and in particular - the settings file
QGIS3.ini, which contains all QGIS program settings.
2.1 Standardization
- Since all program settings made in QGIS are saved in
QGIS3.ini, a manually prepared and configured profile using QGIS can then be distributed as a (standard) copy (e.g. via a network drive, batch script).- The initial settings are based on specifications that are programmed in the software code (visible under: Settings/Options…/Advanced). Individually adjusted values from
QGIS3.inioverride the default specifications.
By distributing a prepared user profile (lets call it settings_template), the entire standardized configuration is finally available as an independent copy on the workstation PCs — even in the case of network installation! — But keep in mind that:
Users could change or delete (basic) settings 
Correction and maintenance
of standard settings are therefore quite complex and possibly protracted (→ individually for each work station)
2.2 Important Settings
- Connections to common data sources (see menu: Layer/Data Source Manager), such as a central PostGIS database or OWS services from the (own) SDI, are usually essential for the organization-wide use of QGIS.
- The connection details can be found in
QGIS3.iniunder the tag[PostgreSQL]or[qgis](OWS)
- This often includes external extensions (plugins), including their environment-dependent configuration such as data source connections, for example:
- norGIS ALKIS-Einbindung — queryable vector layer map from a PostGIS database1) of German cadastre data (ALKIS)
- Discovery — customizable search function on local PostGIS databases
- QGIS Map Library — insert predefined topic layers into the QGIS project at the push of a button.
- Further QGIS configurations for the use of existing, organization-wide resources can include:
- Search path(s) for SVG symbols or additional print templates → on network drives
- User-defined environment variables — which are not required/used until the program has started, e.g.
PGSERVICEFILE2) - special network settings and proxy for web access
- Search filter of the Locator Bar
- …everything else that should be standardized or optimized:
- Colors
- Layouts
Uniform use of specific data and common resources throughout the entire organization- Standardized and at the same time customizable working background and tools at every work station
3. Centralization
- There are various methods for centralizing the QGIS settings and options:
3.1 Start parameters
- Start parameters (command line options) that are called in connection with the QGIS start file. Of particular interest are:
--globalsettingsfile [path]— Using this option, you can specify the path for a Global Settings file, by default%OSGEO4W_ROOT%/resources/qgis_global_settings.ini.- The settings in the specified file replace the original inline default ones, but the user profiles’ settings will be set on top of those!
Placing the qgis_global_settings.inifile on a network shared folder gives a system administrator the possibility to change global settings and defaults in several machines by only editing one file!- There is currently no way to specify the location of certain settings, so a (renamed) copy has to be made manually and supplemented with the corresponding values from QGIS3.ini.3)
Theoretically, you should be able to deliver a completely empty QGIS3.ini, which will later be automatically filled with individual settings.- But Issue #29281 & #29226 require that the [locale]-setting must be included in
QGIS3.ini![locale] userLocale=de_DE overrideFlag=false globalLocale=de_DE showGroupSeparator=false
- As I learned, the Python class
QgsSettingsis required to use qgis_global_settings.ini and replacesQSettings4). This code adjustment must also be followed in external plugins so that their settings are read from qgis_global_settings.ini, see Discovery #73 & Map Library #2. 
--authdbdirectory [path]— Defines, similar to globalsettingsfile, the path to the directory where the authentication database will be stored and loaded.--profiles-path [path]— Specifies a path to load and save the profiles (user settings)- This option allows you to, for instance, carry all your plugins and settings in a flash drive, or, for example, share the settings between different computers using a file sharing service.
--customizationfile [path]— Defines a UI customization file (QGISCUSTOMIZATION3.ini), that will be used at startup.--code [path]— Path to a givenpython file that is run directly after QGIS has started.
3.2 Environment variables
- In some cases you can use an environment variable instead of the command line option.
- It is crucial for the use of environment variables when they have to be available in order to fulfill their purpose!
QGIS_GLOBAL_SETTINGS_FILE→ see above--globalsettingsfileQGIS_CUSTOM_CONFIG_PATH→ see above--profiles-path
These must be set in the (user profile of the) operating system [of the target computer] each time at startup/before QGIS is completely started to take effect. As QGIS system options (see above, standardization point 3. this cannot work!PYQGIS_STARTUP— Points to a Python script that is executed before QGIS starts.
- Options for placing environment variables (on the target computer)
- or moved to a separate file on a network drive
Variables set in this way are unloaded as soon as QGIS is terminated. - Or even during the local QGIS „installation“ using a
.regfile5) on a network drive ( manually set up & export in the Windows registry editor). Command start /wait regedit -s "[network share\]qgis_userEnv.reg"in customized QGIS start file. - [Or via Windows Group / System Policy, which may be installed by the IT department when setting up a Windows user profile. In this way, no modified QGIS start files would be necessary on the target computers, the environment variables are permanently available.]
3.3 Python scripts
- Python scripts — (I haven't used this method yet.)
- Each time QGIS is started, it searches the user directory
%AppData%\Roaming\QGIS\QGIS3for a filestartup.pyand executes it — regardless of the profile used. - With the environment variable
PYQGIS_STARTUP, a Python script (e.g. startup.py) can be executed before the initialization of QGIS is completed. This can be used to copy centrally stored settings etc. to the workstation PCs (→ example).
3)
Since this is neither comfortable nor easy, I hope for the implementation of theQEP #124 "Setting Registry"