/usr/lib/swipl/library/http/http_authenticate.pl
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 http_write_passwd_file(+File, +Data:list) is det
Write password data Data to File. Data is a list of entries as below. See http_read_passwd_file/2 for details. 
passwd(User, Hash, Fields)
To be done
- Write to a new file and atomically replace the old one.