Many useful facilities offered by one or more of the operating systems supported by SWI-Prolog are not supported by the SWI-Prolog kernel distribution. Including these would enlarge the footprint and complicate portability matters while supporting only a limited part of the user-community.
This document describes library(unix) to deal with the
Unix process API,
library(socket) to deal with inet-domain TCP and UDP
sockets, library(cgi) to deal with getting CGI form-data if
SWI-Prolog is used as a CGI scripting language, library(crypt)
to provide password encryption and verification, library(sha)
providing cryptographic hash functions and
library(memfile) providing in-memorty pseudo files.