hadd - Man Page


usage: hadd [-a A] [-k K] [-T T] [-O O] [-v V] [-j J] [-dbg DBG] [-d D] [-n N]
           [-cachesize CACHESIZE]
           [-experimental-io-features EXPERIMENTAL_IO_FEATURES] [-f F]
           [-f[0-9] F[0_9]] [-fk FK] [-ff FF] [-f0 F0] [-f6 F6]


This program will add histograms, trees and other objects from a list of ROOT files and write them to a target ROOT file. The target file is newly created and must not exist, or if -f ("force") is given, must not be one of the source files.



Append to the output


Skip corrupt or non-existent files, do not exit


Do not merge Trees


Re-optimize basket size when merging TTree


Explicitly set the verbosity level: 0 request no output, 99 is the



Parallelize the execution in multiple processes


Parallelize the execution in multiple processes in debug mode (Does

not delete partial files stored inside working directory)


Carry out the partial multiprocess execution in the specified



Open at most 'maxopenedfiles' at once (use 0 to request to use the

system maximum)


Resize the prefetching cache use to speed up I/O operations(use 0 to



Used with an argument provided, enables the corresponding experimental

feature for output trees


Force overwriting of output file.


Gives the ability to specify the compression level of the target file

(by default 4)


Sets the target file to contain the baskets with the same compression

as the input files (unless -O is specified). Compresses the meta data

using the compression level specified in the first input or the

compression setting after fk (for example 206 when using -fk206)


The compression level use is the one specified in the first input


Do not compress the target file


Use compression level 6 (see TFile::SetCompressionSettings for the

supported range of values)


Target file


Source files