$ folderphile --help
folderphile is a diff / merge editor (depending on whether "base" is set)
that recursively compares two folders ("left" and "right").
Usage:
folderphile [opts]
Flags:
-b, --base string base is the common ancestor of left and right; implies merge
-l, --left string side to compare
-r, --right string side to compare
-o, --output string output is the destination
-h, --help help for folderphile
-v, --version version for folderphile