>Hello,
>I want to create a error log file, but I don't know how to write to a file without loosing the existing text.
>Is there a easy way to write "additive" to file?

If you use ?/?? for output to a file using SET PRINTER, you can:

SET PRINTER TO File name ADDITIVE
SET PRINTER ON

You can also use

SET ALTERNATE TO File Name ADDITIVE
SET ALTERNATE ON

to do the same thing

If you use low-level file I/O, you can use an FOPEN() if the file exists to open the file for output, and then immediately do an FSEEK() to get to the end of file, something like:

nFH = FOPEN('C:\Some\Text\File',12) && open read-write, buffered
=FSEEK(nFH,0,2) && Move to end of file