Error on dbase extesion exec php

Question

When I use exec to use a script

exec('nohup php /excel.php  >> /log.log & echo $!', $output);

with dbase extension => dbase_open('file.dbf', 0);

php dont reconize dbase extension and return the error

Call to undefined function dbase_open()

if i use script without exec dbase works well

I think I need load something