Read the gitattributes documentation :
Defining a custom merge driver
The definition of the merge driver is done in the .git / config file and not in the gitattributes file, so strictly speaking, this manual page is the wrong place to talk about it. But...
To define a custom merge filfre file, add a section to the $ GIT_DIR / config file (or the $ HOME / .gitconfig file), for example:
[merge "filfre"] name = feel-free merge driver driver = filfre %O %A %B recursive = binary
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