Modern C Compiler, ROOT, Geant

Introduction

So you want a modern C compiler and/or some other tool. As of this writing (2 November 2016) the normal desktop machines have

gcc version 4.4.7 20120313 (Red Hat 4.4.7-17) (GCC)

as the default compiler. This is not recent enough for much of the HEP code ecosystem.

Modern C compilers can be found in a repository called "SFT" which is maintained by CERN, and distributed via something called CVMFS which is installed on stoomboot machines and most of the desktop machines (older ones may not have it). You can check whether you have it with:

ls /cvmfs/sft.cern.ch

if you don't get an error (and it says "lcg") then you're good. What you'll need to do to set up the compiler is:

1. figure out what kind of platform you'll be running on
2. poke around in SFT to find out what the current release is
3. run the setup script
4. compile your code and win the Nobel Prize.

Figure out your platform

You'll generally need to compile for a specific platform; go (one of) the machine(s) on which you'll be running your code and type

cat /etc/issue

Today on one of the stoomboot worker nodes, it says

Scientific Linux CERN SLC release 6.8 (Carbon)
Kernel \r on an \m

Remember that first line, that tells you the platform, you'll need it shortly.

Poke around in SFT and find the relevant release and compiler

stbc-i2:~> cd /cvmfs/sft.cern.ch/lcg/releases
stbc-i2:releases> ls -d LCG_* 
LCG_71	     LCG_81c	     LCG_82rootaas4  LCG_84swan3  LCG_86
LCG_71root6  LCG_81d	     LCG_82rootaas5  LCG_84swan4  LCG_87
LCG_72a      LCG_81e	     LCG_82rootaas6  LCG_85	  LCG_latest
LCG_75root6  LCG_81f	     LCG_83	     LCG_85a	  LCG_rootext20161010
LCG_78root6  LCG_82	     LCG_84	     LCG_85b	  LCG_rootext20161129
LCG_79	     LCG_82rootaas1  LCG_84a	     LCG_85swan1
LCG_80	     LCG_82rootaas2  LCG_84swan1     LCG_85swan2
LCG_81b      LCG_82rootaas3  LCG_84swan2     LCG_85swan3

Note the LCG87 is the highest number ... this is generally the latest full release. Take a look at this page for some documentation on what the various releases include.

Note I've replaced below, "LCG_87" with "LCG_XXX" in commands to help avoid mistakes made via blind copy-and-pasting. Change the XXX to whatever you find the most recent release to be!

stbc-022:releases> cd /cvmfs/sft.cern.ch/lcg/releases/LCG_XXX
stbc-i2:LCG_XXX> ls
4suite		 gmp					      LCG_externals_x86_64-ubuntu1604-gcc54-dbg.txt   pacparser        requests
AIDA		 gperftools				      LCG_externals_x86_64-ubuntu1604-gcc54-opt.txt   pandas	       ROOT
astroid		 graphviz				      LCG_generators_x86_64-centos7-gcc62-dbg.txt     pathlib2	       root_numpy
autoconf	 Grid					      LCG_generators_x86_64-centos7-gcc62-opt.txt     pathos	       rootpy
automake	 GSL					      LCG_generators_x86_64-slc6-gcc49-dbg.txt	      pcre	       rpy2
backports	 gtest					      LCG_generators_x86_64-slc6-gcc49-opt.txt	      pexpect	       scikitlearn
blas		 hadoop					      LCG_generators_x86_64-slc6-gcc62-dbg.txt	      pickleshare      scipy
Boost		 hepdata_converter			      LCG_generators_x86_64-slc6-gcc62-opt.txt	      pip	       setuptools
castor		 hepdata_validator			      LCG_generators_x86_64-ubuntu1604-gcc54-dbg.txt  pkg_config       simplegeneric
ccache		 HepMC					      LCG_generators_x86_64-ubuntu1604-gcc54-opt.txt  pox	       simplejson
certifi		 HepPDT					      lcov					      ppft	       singledispatch
clhep		 hive					      lhapdfsets				      prettytable      sip
CMake		 igprof					      libaio					      processing       six
cmaketools	 ipykernel				      libgit2					      prompt_toolkit   sollya
cmmnbuild	 ipython				      libsvm					      protobuf	       soqt
cmt		 ipython_genutils			      libtool					      psutil	       spark
coin3d		 ipywidgets				      libunwind					      ptyprocess       sqlalchemy
configparser	 java					      libxml2					      py	       sqlite
COOL		 jemalloc				      libxslt					      py2neo	       stomppy
CORAL		 Jinja2					      logilabcommon				      py4j	       storm
CouchDB		 joblib					      lxml					      pyanalysis       subprocess32
coverage	 jpype					      m4					      pyapigitlab      swig
cppgsl		 jsonc					      MarkupSafe				      pydot	       sympy
CppUnit		 jsoncpp				      matplotlib				      pydot_ng	       tbb
curl		 jsonschema				      maven					      pygments	       terminado
cx_oracle	 jupyter				      MCGenerators				      pygraphics       theano
cycler		 jupyter_client				      messaging					      pygsi	       tornado
cython		 jupyter_console			      metakernel				      pylint	       traitlets
Davix		 jupyter_contrib_core			      mistune					      pyminuit	       urllib3
DD4hep		 jupyter_contrib_nbextensions		      mock					      pyparsing        uuid
decorator	 jupyter_core				      mpfi					      pyqt	       valgrind
dill		 jupyter_nbextensions_configurator	      mpfr					      pyqt5	       vdt
distribute	 keras					      mpich2					      pytest	       VecGeom
doxygen		 lapack					      multiprocess				      Python	       vectorclass
eigen		 LCGCMT					      multiprocessing				      python_dateutil  wcwidth
elasticsearch	 LCG_contrib_x86_64-centos7-gcc62-dbg.txt     mysql					      python_gitlab    wheel
entrypoints	 LCG_contrib_x86_64-centos7-gcc62-opt.txt     mysql_python				      pytimber	       widgetsnbextension
expat		 LCG_contrib_x86_64-slc6-gcc49-dbg.txt	      nbconvert					      pytools	       xapian
fastjet		 LCG_contrib_x86_64-slc6-gcc49-opt.txt	      nbformat					      pytz	       XercesC
fftw3		 LCG_contrib_x86_64-slc6-gcc62-dbg.txt	      networkx					      pyxml	       xqilla
fjcontrib	 LCG_contrib_x86_64-slc6-gcc62-opt.txt	      neurobayes				      pyyaml	       xrootd
fplll		 LCG_contrib_x86_64-ubuntu1604-gcc54-dbg.txt  neurobayes_expert				      pyzmq	       xrootd_python
freetype	 LCG_contrib_x86_64-ubuntu1604-gcc54-opt.txt  ninja					      QMtest	       xz
frontier_client  lcgenv					      nose					      qt	       yamlcpp
ftjam		 LCG_externals_x86_64-centos7-gcc62-dbg.txt   notebook					      qt5	       zeromq
future		 LCG_externals_x86_64-centos7-gcc62-opt.txt   numexpr					      qtconsole        zlib
futures		 LCG_externals_x86_64-slc6-gcc49-dbg.txt      numpy					      qwt
gcc		 LCG_externals_x86_64-slc6-gcc49-opt.txt      omniorb					      R
Geant4		 LCG_externals_x86_64-slc6-gcc62-dbg.txt      openssl					      rangev3
genshi		 LCG_externals_x86_64-slc6-gcc62-opt.txt      oracle					      RELAX

There is a lot of stuff in here that might be interesting to you (eg ROOT and Geant4). See that gcc is also listed, list that directory to see the options:

stbc-i2:LCG_87> ls gcc
4.9.1  4.9.3  6.2.0
stbc-i2:LCG_87> ls gcc/4.9.3
x86_64-slc6

So gcc 4.9.3 is there, along with two other versions. Now the /etc/issue business above becomes relevant: it said "Scientific Linux CERN SLC release 6.8" which corresponds to the "slc6" here, so this one will work for you:

stbc-i2:LCG_87> ls gcc/4.9.3/x86_64-slc6
bin  include  lib  lib64  libexec  setup.csh  setup.csh~  setup.sh  setup.sh~  share

Run the setup script

You want that setup.sh file ..

source /cvmfs/sft.cern.ch/lcg/releases/LCG_XXX/gcc/X.Y.Z/x86_64-platform/setup.sh

Change XXX to the right LCG release tag, X.Y.Z to the right gcc version you found, and "platform" to the right platform you found.

note: csh users need the setup.csh file We (PDP) assume that the csh setup works correctly, none of us use csh, hence we don't know for sure ;-)

Compile your code

Now you'll have the right stuff in your path, etc to use this version of gcc:

stbc-022:x86_64-slc6> gcc --version
gcc (GCC) 4.9.3
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

stbc-022:x86_64-slc6> g++ --version
g++ (GCC) 4.9.3
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Enjoy that prize. Don't forget to mention the PDP group in your speech.