This is the command hadd that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
hadd - Merge ROOT histogram files into one file
hadd outputfile inputfiles ...
This program will add histograms from a list of ROOT files and write them to a target ROOT
file. The target file is newly created and must not be identical to one of the source
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