bup midx [options...] <idxnames...>
--
o,output= output midx filename (default: auto-generated)
-a,auto automatically create .midx from any unindexed .idx files
-f,force automatically create .midx from *all* .idx files
+a,auto automatically use all existing .midx/.idx files as input
+f,force merge produce exactly one .midx containing all objects
p,print print names of generated midx files
max-files= maximum number of idx files to open at once [-1]
dir= directory containing idx/midx files