AMIGASYSTEM
I was a little rusty, but it started coming back to me.
There were two errors in the code for DirTree. After I corrected them then I could compile at the commanline using gcc using:
gcc dirtree.c -o dirtree
Then I copied it to the C directory and it functioned the same as the original executable included with the source files.
Here are the two corrections: In the struct at the beginning for "Global" on line 96 the value was LONG * but the function expects IPTR * so...
IPTR opts[NOPTS];
Lastly on line 335 the DateTime flag can either be set or not set but it can't be NULL apparently. It only accepts value "DTF_SUBST" so...
//g->dt.dat_Flags = NULL;
g->dt.dat_Flags = DTF_SUBST;
The nice part of DirTree is that you can direct the output to a text file such as: "dirtree system:devs nohead >file.log"
Here is the code file attached.