Prolog: adding text to the end of a file

I want to add text to a database in prolog. Something like

adding :- tell('a.txt'), write('abc'), told.

but not overwriting the a.txt. I've tried using append like 开发者_开发问答this:

append('a.txt'),write('abc'), told.

but it didn't work. The listener just give a 'no' response and file is not changed. I'm using Amzi Prolog, btw.

Any help will be appreciated.

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You have to use these IO predicates: open/3, write/2, close/1.

adding :- open('a.txt', append, Handle), write(Handle, 'abc'), close(Handle).

Check here

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In SWI-Prolog this works:

?- append('a.txt'), write('abc'), told.
true.

?- append('a.txt'), write('abc'), told.
true.

Maybe Amzi Prolog does not have append/1 and this causes failure rather than an exception. Or maybe the file is not writable (and this causes failure, rather than an exception).