Processing /home/alitrain/train-steer/extract_syswatch.C... E-TFile::TFile: file syswatch.root does not exist #0 0x00007f22c9bbf89e in waitpid () from /lib64/libc.so.6 #1 0x00007f22c9b514e9 in do_system () from /lib64/libc.so.6 #2 0x00007f22ce1cafdb in TUnixSystem::Exec (shellcmd=, this=0xa55570) at /build/workarea/sw/20156032/1/SOURCES/ROOT/v6-16-00/v6-16-00/core/unix/src/TUnixSystem.cxx:2119 #3 TUnixSystem::StackTrace (this=0xa55570) at /build/workarea/sw/20156032/1/SOURCES/ROOT/v6-16-00/v6-16-00/core/unix/src/TUnixSystem.cxx:2413 #4 0x00007f22c42c70e5 in cling::MultiplexInterpreterCallbacks::PrintStackTrace() () from /cvmfs/alice.cern.ch/el6-x86_64/Packages/ROOT/v6-16-00-18/lib/libCling.so #5 0x00007f22c42c6aeb in cling_runtime_internal_throwIfInvalidPointer () from /cvmfs/alice.cern.ch/el6-x86_64/Packages/ROOT/v6-16-00-18/lib/libCling.so #6 0x00007f22ceb6e79e in ?? () #7 0x00000000000f1220 in ?? () #8 0x00000000049302c0 in ?? () #9 0x00007f22c9ea1120 in ?? () from /lib64/libc.so.6 #10 0x00000000000ccd40 in ?? () #11 0x0000000000000001 in ?? () #12 0x00000000c9b8bc88 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/v6-16-00-18/include/TFile.h:335:15: note: expanded from macro 'gFile' #define gFile (TFile::CurrentFile()) ^~~~~~~~~~~~~~~~~~~~~~