4.9. Using the command-line interface (CLI)

In addition to the graphical user interface, the Importer/Exporter also comes with a command-line interface (CLI) letting you execute the main operations of the Importer/Exporter on your command prompt. The CLI also allows you to easily embed the Importer/Exporter in batch processing workflows and third-party applications, and to run in from within a Docker container.

To launch the CLI, simply execute the impexp start script on the command line. The script is located in the bin folder within the installation directory of your Importer/Exporter. Depending on your platform, it comes in two flavors:

  • impexp.bat (Microsoft Windows family)
  • impexp (UNIX/Linux/Mac OS family)

The CLI is launched with default options for the Java Virtual Machine (JVM) that runs the application. You can override these default options in the launch process by using the environment variable JAVA_OPTS. More information is available in Section 4.1.


For convenience, it is recommended to add the impexp executable to your path. Use one of the following commands to do so.

Windows: set PATH=C:\path\to\3DCityDB-Importer-Exporter\bin;%PATH%
Linux: export PATH=/path/to/3DCityDB-Importer-Exporter/bin:$PATH


Instead of using the predefined start script, you can also directly invoke the JAR file impexp-client-<version>.jar in the lib folder of the installation directory, which implements the command-line interface. This way, you have full control over the Java runtime and options for executing the CLI. Use the following command as starting point.

java [JVM_OPTIONS] -jar lib/impexp-client-cli-<version>.jar [CLI_OPTIONS]


impexp [-hV] [--ade-extensions=<folder>] [-c=<file>] [--log-file=<file>]
       [--log-level=<level>] [--pid-file=<file>] [--plugins=<folder>]
       >...]]... [@<filename>...] COMMAND


The impexp interface offers a number of commands to interact with the 3D City Database and to execute import, export and delete operations. The commands have their own options and parameters and are discussed in separate sections of this chapter.

Table 4.31 Commands offered by the command-line interface
Displays help information about the specified command.
Imports data in CityGML or CityJSON format.
Exports data in CityGML or CityJSON format.
Exports data in KML/COLLADA/glTF format for visualization.
Deletes top-level city objects from the database.
Validates input files against their schemas.
Starts the graphical user interface.


Plugins can add their own commands to the command-line interface. Thus, the list of available commands may increase depending on the number of plugins you have registered with the Importer/Exporter. Please refer to the user manual of your plugin for a documentation of the plugin-specific commands.

You are required to pass the COMMAND to be executed as mandatory input to the impexp interface. Otherwise, the tool will terminate and print a general help message to the terminal.

The command-line tool uses exit codes to signify success or failure of an operation. In general, the value 0 means success, 1 means the operation aborted abnormally due to errors, and 2 indicates invalid input for an option or parameter. The separate commands may add their own operation-specific exit codes to this list.

Just like with the graphical user-interface, you can use the environment variable JAVA_OPTS in the launch process of the CLI to provide options to the Java Virtual Maching (JVM) that runs the tool. For example, you can adapt the amount of main memory that shall be available for the Importer/Exporter. Please refer to Section 4.1 for how to use the JAVA_OPTS variable. Export users may also directly adapt the impexp start script.

More general functionalities and usage information for the command-line tool are discussed in Section 4.9.9.

Global options

The impexp main command provides global options that can be used with all commands. On the command line, you are free to put them in front of or after the COMMAND that you want to execute.


The name of the COMMAND to execute.

-c, --config=<file>

Use the settings from the specified XML config file for the command to be executed. In general, every command provides a set of command-line options to adapt its behaviour to your needs. These options are meant to cover the most common use cases but do not reflect all settings available from the graphical user interface. If you miss specific settings, you can provide a config file in addition or even instead of the command-line options offered by the command. Note that settings specified through command-line options always take precedence over settings from a config file.

The easiest way to create a config file is to run the Importer/Exporter in GUI mode, make all required settings, and then save the settings to a file using “File -> Save Settings As…” from the menu bar. You can directly use the resulting file or adapt it to your needs before feeding it to the CLI. Of course, you can also create the config file fully automatically and only with the content you need. Either way, make sure the config file is valid with respect to the XML Schema definition of the Importer/Exporter. You can easily get a copy of the XSD file via the “File -> Save Settings XSD As…” entry from the menu bar.


You can also create a config file programmatically in Java. The JAR file impexp-config-{version}.jar in the lib folder of the installation directory contains all the classes required for reading and writing a config file. Once you have the JAR file on your classpath, use the class org.citydb.config.ConfigUtil as starting point.


Log level to be used for printing log messages to the terminal and a log file. Valid values are error, warn, info, and debug (default: info). See also Section 4.7.7.


If you want the log messages to be printed to a log file in addition to the terminal, provide the full path to the log file with this option. The file will be truncated if it already exists.


Create a file containing the process ID (PID) of the impexp tool at the specified path. The PID can be used, for instance, to check whether the process is still running or to send signals to the process. The PID file is automatically deleted when the impexp tool terminates.


Provide an alternative path where to look for Importer/Exporter plugins. By default, plugins are searched for in the plugins folder within the installation directory of the Importer/Exporter.


Comma-separated list of plugins that shall be enabled (default: true) or disabled (false) on startup. Use the fully qualified class name of the plugin to uniquely identify it. Disabling unnecessary plugins can increase performance.


Provide an alternative path where to look for ADE extensions. By default, ADE extensions are searched for in the ade-extensions folder within the installation directory of the Importer/Exporter.


When creating a command line with lots of options or with long arguments for options, you might run into system limitations on the length of the command line. Argument files (@-files) are a way to overcome this problem. Argument files are files that themselves contain arguments to the command. You can provide one or more argument files on the command line by simply prefixing their filenames with the character @. The content of each @-file is automatically expanded into the argument list. See Section for more information.

-h, --help

Display a help message for the specified command and exit.

-V, --version

Print version information and exit.