  Filamentary structures are ubiquitous in high-mass star-forming molecular
clouds. Their relation with high-mass star formation is still to be understood.
Here we report interferometric observations toward 8 filamentary high-mass
star-forming clouds. A total of 50 dense cores are identified in these clouds,
most of which present signatures of high-mass star formation. Five of them are
not associated with any star formation indicators, hence are prestellar core
candidates. Evolutionary phases of these cores and their linewidths,
temperatures, NH$_3$ abundances, and virial parameters are found to be
correlated. In a sub-sample of 4 morphologically well-defined filaments, we
find that their fragmentation can not be solely explained by thermal or
turbulence pressure support. We also investigate distributions of gas
temperatures and non-thermal motions along the filaments, and find a spatial
correlation between non-thermal linewidths and star formation activities. We
find evidence of gas flows along these filaments, and derive an accretion rate
along filaments of $\sim$10$^{-4}$ M$_\odot$ yr$^{-1}$. These results suggest a
strong relationship between massive filaments and high-mass star formation,
through i) filamentary fragmentation in very early evolutionary phases to form
dense cores, ii) accretion flows along filaments that are important for the
growth of dense cores and protostars, and iii) enhancement of non-thermal
motion in the filaments by the feedback or accretion during star formation.
