Add systemd service file
Operate on file descriptors instead of files

Instead of the previous tedious process:

                  fprintf
             /                \
dup - fdopen                    fclose
             \                /
               fseek - fscanf

We can just do:

        write
      /
lseek
      \
        read

on the file descriptor and be done.
Use an error checking macro
Use LLVM style