18.10. Environment Variables Frequently Asked Questions

What are the most important environment variables that affect the behavior of Fast DDS?

FASTDDS_DEFAULT_PROFILES_FILE, SKIP_DEFAULT_XML, FASTDDS_BUILTIN_TRANSPORTS, ROS_DISCOVERY_SERVER, ROS_SUPER_CLIENT, FASTDDS_STATISTICS, FASTDDS_ENVIRONMENT_FILE. For further information, refer to Environment variables.

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What is the purpose of the "FASTDDS_DEFAULT_PROFILES_FILE" environment variable?

Defines the location of the default profile configuration XML file. For further information, refer to FASTDDS_DEFAULT_PROFILES_FILE.

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What happens when the variable "SKIP_DEFAULT_XML" is set to 1?

Skips looking for a default profile configuration XML file. If this variable is set to 1, Fast DDS will load the configuration parameters directly from the classes’ definitions without looking for the DEFAULT_FASTDDS_PROFILES.xml in the working directory. For further information, refer to SKIP_DEFAULT_XML.

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What is the primary purpose of the "FASTDDS_BUILTIN_TRANSPORTS" environment variable?

Setting this variable allows to modify the builtin transports that are initialized during the DomainParticipant creation. For further information, refer to FASTDDS_BUILTIN_TRANSPORTS.

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What is the purpose of the "ROS_DISCOVERY_SERVER" environment variable?

Setting this variable configures the DomainParticipant to connect to one or more servers using the Discovery Server discovery mechanism. For further information, refer to ROS_DISCOVERY_SERVER.

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What happens to a "DomainParticipant" when its discovery protocol is set to "SIMPLE" and "ROS_SUPER_CLIENT" is set to TRUE?

If the DomainParticipant’s discovery protocol is set to SIMPLE, and ROS_SUPER_CLIENT is set to TRUE, the participant is automatically promoted to a SUPER_CLIENT. For further information, refer to ROS_SUPER_CLIENT.

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What is the purpose of setting the "FASTDDS_STATISTICS" environment variable, according to the provided information?

Setting this variable configures the DomainParticipant to enable the statistics DataWriters which topics are contained in the list set in this environment variable. For further information, refer to FASTDDS_STATISTICS.

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What happens when you set the "FASTDDS_ENVIRONMENT_FILE" environment variable to a JSON file?

Setting this environment variable to an existing json file allows to load the environment variables from the file instead of from the environment. For further information, refer to FASTDDS_ENVIRONMENT_FILE.