How can I setup an ODBC data source for c-treeRTG on Linux?

You can use a generic ODBC manager library to connect to c-treeRTG, similar to how it is done in Windows.
One of the most common is the unixODBC library.
This software may not be installed on your system. Use a command like this to install it:

   sudo apt install unixodbc

Here's how to configure the c-tree ODBC driver and create and test a DSN on Linux.

Define the c-tree driver: edit the file /etc/odbcinst.ini, e.g.
```
    [ctreeDriver]
    Driver=/path/to/libctodbc.so
    Description=ODBC for c-treeRTG
    FileUsage=1
```
Note - The libctodbc.so library is installed along with c-tree in the "drivers/ctree.drivers/lib" subfolder.

Create a DSN bound to this driver: edit the file /etc/odbc.ini, e.g.

    Driver=ctreeDriver
    Host=localhost
    Database=ctreeSQL
    Service=6597
    Description=ctreeSQL data source

To allow the unixODBC library to install the odbcinst and odcini you must execute the following commands:
```
    odbcinst -i -d -f /etc/odbcinst.ini
    odbcinst -i -s -l -f /etc/odbc.ini 
```
You can test if your DSN is installed by executing:
```
    odbcinst -s -q
```
Expected result: [ctreeDSN]
Set the ODBCINI environment variable, e.g.
```
    export ODBCINI=/etc/odbc.ini
```
Check that your unixODBC is configured for c-tree by running a tool connected to a unixODBC data source.
For example, you can execute unixODBC's Interactive SQL (isql) from /usr/bin as shown below:
```
    isql -v ctreeDSN admin ADMIN
```

More information is given in the FairCom documentation here.