Processing /home/alitrain/train-steer/extract_syswatch.C... E-TFile::TFile: file syswatch.root does not exist #0 0x00007f98b3b6f89e in waitpid () from /lib64/libc.so.6 #1 0x00007f98b3b014e9 in do_system () from /lib64/libc.so.6 #2 0x00007f98b817afdb in TUnixSystem::Exec (shellcmd=, this=0x1dea570) at /build/workarea/sw/20156006/1/SOURCES/ROOT/v6-16-00/v6-16-00/core/unix/src/TUnixSystem.cxx:2119 #3 TUnixSystem::StackTrace (this=0x1dea570) at /build/workarea/sw/20156006/1/SOURCES/ROOT/v6-16-00/v6-16-00/core/unix/src/TUnixSystem.cxx:2413 #4 0x00007f98ae2770e5 in cling::MultiplexInterpreterCallbacks::PrintStackTrace (this=) at /build/workarea/sw/20156006/1/SOURCES/ROOT/v6-16-00/v6-16-00/interpreter/cling/lib/Interpreter/MultiplexInterpreterCallbacks.h:133 #5 0x00007f98ae276aeb in cling_runtime_internal_throwIfInvalidPointer (Interp=0x1eab0b0, Expr=0x5acae48, Arg=) at /build/workarea/sw/20156006/1/SOURCES/ROOT/v6-16-00/v6-16-00/interpreter/cling/lib/Interpreter/Exception.cpp:42 #6 0x00007f98b8b1e79e in ?? () #7 0x00000000000983d0 in ?? () #8 0x0000000005d2db40 in ?? () #9 0x00007f98b3e51120 in ?? () from /lib64/libc.so.6 #10 0x000000000003b4c0 in ?? () #11 0x0000000000000001 in ?? () #12 0x00000000b3b3bc88 in ?? () #13 0x0000000000000000 in ?? () E-HandleInterpreterException: Trying to dereference null pointer or trying to call routine taking non-null arguments. Execution of your code was aborted. In file included from input_line_33:1: /home/alitrain/train-steer/extract_syswatch.C:28:26: warning: null passed to a callee that requires a non-null argument [-Wnonnull] TTree *tree = (TTree*) gFile->Get("syswatch"); ^~~~~ /cvmfs/alice.cern.ch/el6-x86_64/Packages/ROOT/v6-16-00-10/include/TFile.h:335:15: note: expanded from macro 'gFile' #define gFile (TFile::CurrentFile()) ^~~~~~~~~~~~~~~~~~~~~~