Folders and PLCnext Technology environment variables
The following table lists environment variables on the controller, representing directories that are required for app administration. The values of these environment variables are set to the defaults shown below, using information in the file /etc/plcnext/Device.acf.settings. These default values do not need to be changed by app developers or app users.
Note: Paths/directories on the system may differ depending on the PLCnext Control device generation. The following generations are available:
- First generation of PLCnext Control devices
- Secure-by-default generation of PLCnext Control devices
For more information, see Directories of the firmware components in the PLCnext Technology ‑ Info Center.
| Environment variable | Value | Use |
| ARP_PATH_HOME_DIR | /opt/plcnext | Working directory of the PLCnext Technology Runtime |
| ARP_PATH_APPS_INSTALL_DIR Introduced in the PLCnext Technology firmware from version 2025.0 |
First generation of PLCnext Control devices: $ARP_PATH_HOME_DIR$/installed_apps Secure-by-default generation of PLCnext Control devices: $ARP_PATH_HOME_DIR$/apps/mounted |
Installation directory of the PLCnext Technology app containers |
| ARP_PATH_APPS_ACTIVE_DIR | First generation of PLCnext Control devices: $ARP_PATH_HOME_DIR$/apps Secure-by-default generation of PLCnext Control devices: $ARP_PATH_HOME_DIR$/apps/mounted |
Contains the folders of the mounted app containers. |
| ARP_PATH_APPS_HOME_DIR | First generation of PLCnext Control devices: $ARP_PATH_HOME_DIR$/appshome Secure-by-default generation of PLCnext Control devices: $ARP_PATH_HOME_DIR$/apps/installed |
All app data such as persistent memory and symlinks to determine binaries are stored here. |
| ARP_PATH_APPS_DATA_DIR | $ARP_PATH_APPS_HOME_DIR$/data | Represents the root storage folder for persistent app data. |
| ARP_PATH_APPS_TEMP_DIR | /var/tmp/appsdata | Represents the root storage folder for temporary data of the apps. |
| ARP_PATH_APPS_BIN_DIR | $ARP_PATH_APPS_HOME_DIR$/bin |
Storage directory for the symlinks to the command line tools of the apps. |
See also