Which GCC version do I have on my OS X Sierra

Question

When I type gcc -v , I get :

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-apple-darwin14.0.0/4.9.2/lto-wrapper
Target: x86_64-apple-darwin14.0.0
Configured with: ../gcc-4.9-20141029/configure --enable-languages=c++,fortran
Thread model: posix
gcc version 4.9.2 20141029 (prerelease) (GCC) 

So my gcc version is 4.9.2 However, when I try to install gcc again by typing : brew tap homebrew/versions; brew install gcc --without-multilib brew tap homebrew/versions; brew install gcc --without-multilib I get :

Updating Homebrew...
==> Auto-updated Homebrew!
Updated 3 taps (homebrew/core, homebrew/science, homebrew/versions).
==> New Formulae
git-quick-stats                 homebrew/science/med-file       ktmpl
==> Updated Formulae
aha                             homebrew/science/bowtie         mpd
akka                            homebrew/science/cdo            mysql-cluster
arangodb                        homebrew/science/matplotlib     no-more-secrets
buku                            homebrew/science/packmol        nvm
bullet                          homebrew/science/paraview       protobuf-swift
casperjs                        homebrew/science/pymol          qca
certigo                         imagemagick ✔                   ringojs
chicken                         imagemagick@6                   rust
cjdns                           jenkins                         skinny
coffeescript                    jigdo                           sqldiff
compcert                        jump                            sqlite-analyzer
crystal-lang                    kobalt                          svtplay-dl
dbhash                          libhdhomerun                    swiftgen
digdag                          libphonenumber                  vim
direnv                          libsigsegv                      wakatime-cli
elixirscript                    mapserver                       wolfssl
embulk                          mecab-jumandic                  yank
geoserver                       mkvtoolnix                      yaz
gitlab-ci-multi-runner          mosquitto
==> Deleted Formulae
bip                             homebrew/versions/openssl101    probatron4j
edelta                          lcab                            rtpbreak
esound                          malaga

Updating Homebrew...
Warning: gcc-6.3.0_1 already installed 

This output says at the end that I have gcc 6.3 . Am I working with gcc 4.9.2 or gcc 6.3 ?

PS : If you are interested in why I executed the brew tap & brew install commands, it is because I am trying to install xgboost in python. In the github repo of xgboost , they're advising to run the above commands before installation to get the latest g++ compiler.

Answer 1

To address your question "Am I working with gcc 4.9.2 or gcc 6.3"

You are still working with gcc 4.9.2.

How can you make gcc-6 your default compiler? See below:

sudo ln -s <path-to>/gcc-6 <path-to>/gcc

Reload and verify

Now exit the terminal session and open a new terminal (so the links update) and type gcc -v and see if the version is now the latest.

Other related tools

NOTICE: You may also wish to update c++ -> c++-6 , g++ -> g++-6 , and cpp -> cpp-6 in a similar fashion, just repeat the above step for each in turn, ALWAYS BACKUP in case something goes wrong so you can undo everything if necessary.

NOTE:

If you get a "Operation not permitted" warning and you are using El Capitan or newer version of Mac OS X please see this question/answer on how to disable the security feature that is preventing you from making changes to /usr/bin directory:

https://superuser.com/questions/933019/sudo-cant-create-file-in-usr-bin-in-el-capitan