Forbes will have a player option in the second year of the deal, a source told Wojnarowski.
Portis, 25, averaged 10.1 points and 5.1 rebounds per game for the Knicks last season, his fifth in the National Basketball Association.
The Bucks have replenished their bench in free agency, adding guards Forbes and D.J.
Covid-19: Four Further Deaths, 344 Additional Cases John Hopkins University data as of Saturday showed 12,051,253 cases and 255,588 deaths have been reported in the U.S. As of 2pm today, 283 people were being treated for the illness in hospital with 33 of those patients in ICU.
Suiting up in 57 regular-season games for the Magic in 2019-20, Augustin averaged 10.5 points and 4.6 assists per contest.
He is coming off a season in which both his field goal percentage (39.9) and 3-point percentage (34.8) took significant dips.
Free agent guard Jaylen Adams also agreed to a two-way deal with the Bucks on Saturday, his agents told ESPN.
Craig went undrafted in the 2014 NBA Draft and played for different teams in Australia's National Basketball League (NBL) before finding his way to the Nuggets three seasons later.