  A precise prediction of the neutrino flux is a key ingredient for achieving
the physics goals of long-baseline neutrino experiments. In modern
accelerator-based neutrino experiments, neutrino beams are created from the
decays of secondary hadrons produced in hadron-nucleus interactions. Hadron
production is the leading systematic uncertainty source on the neutrino flux
prediction; therefore, its precise measurement is essential. The NA61/SHINE is
a fixed-target experiment at the CERN Super Proton Synchrotron, which studies
hadron production in hadron-nucleus and nucleus-nucleus collisions for various
physics goals. For neutrino physics, light hadron beams (protons, pions, and
kaons) are collided with a light nuclear target (carbon, aluminum, and
beryllium) and spectra of outgoing hadrons are measured. These proceedings will
review the recent results and ongoing hadron production measurements with
NA61/SHINE for the precise neutrino flux predictions in the T2K and Fermilab
long-baseline neutrino experiments. It will also discuss the prospects for
future hadron production measurements with NA61/SHINE beyond 2020, after the
Long Shutdown 2 of the accelerator complex at CERN.
