how to find gcc version on mac

In case you installed gcc via brew install, it might've got installed as gcc-11.

You can run brew info gcc to get path where it is installed and get exact name of the binary by listing the directory.

$ brew info gcc
gcc: stable 11.2.0 (bottled), HEAD
GNU compiler collection
https://gcc.gnu.org/
/usr/local/Cellar/gcc/11.2.0_3 (2,163 files, 459.8MB) *
...

$ ls /usr/local/Cellar/gcc/11.2.0_3/bin
c++-11                  gcc-ar-11               gcov-dump-11                gfortran                x86_64-apple-darwin21-g++-11        x86_64-apple-darwin21-gcc-ranlib-11
cpp-11                  gcc-nm-11               gcov-tool-11                gfortran-11             x86_64-apple-darwin21-gcc-11        x86_64-apple-darwin21-gcc-tmp
g++-11                  gcc-ranlib-11               gdc                 lto-dump-11             x86_64-apple-darwin21-gcc-ar-11     x86_64-apple-darwin21-gdc-11
gcc-11                  gcov-11                 gdc-11                  x86_64-apple-darwin21-c++-11        x86_64-apple-darwin21-gcc-nm-11     x86_64-apple-darwin21-gfortran-11

Then using gcc-11 -v will get you actual version of gcc installed.

$ gcc-11 -v
Using built-in specs.
COLLECT_GCC=gcc-11
COLLECT_LTO_WRAPPER=/usr/local/Cellar/gcc/11.2.0_3/bin/../libexec/gcc/x86_64-apple-darwin21/11/lto-wrapper
Target: x86_64-apple-darwin21
Configured with: ../configure --prefix=/usr/local/opt/gcc --libdir=/usr/local/opt/gcc/lib/gcc/11 --disable-nls --enable-checking=release --with-gcc-major-version-only --enable-languages=c,c++,objc,obj-c++,fortran,d --program-suffix=-11 --with-gmp=/usr/local/opt/gmp --with-mpfr=/usr/local/opt/mpfr --with-mpc=/usr/local/opt/libmpc --with-isl=/usr/local/opt/isl --with-zstd=/usr/local/opt/zstd --with-pkgversion='Homebrew GCC 11.2.0_3' --with-bugurl=https://github.com/Homebrew/homebrew-core/issues --enable-libphobos --build=x86_64-apple-darwin21 --with-system-zlib --disable-multilib --with-native-system-header-dir=/usr/include --with-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX12.sdk
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.2.0 (Homebrew GCC 11.2.0_3) 

The tools supplied by Apple have been switched from GCC to Clang. The gcc command is linked to clang as a convenience. In OS X 10.9, you do not have GCC on your system unless you have installed it independently of Apple packages.

You seem to not actually have gcc on your path. As of recent versions of Xcode, it installs a "gcc" that is instead a link to Clang.

gcc -dumpversion | cut -f1 -d.

-dumpversion Print the compiler version (for example, 3.0) — and don't do anything else.

The same works for following compilers/aliases:

cc -dumpversion
g++ -dumpversion
clang -dumpversion
tcc -dumpversion

Be careful with automate parsing the GCC output:

• Output of --version might be localized (e.g. to Russian, Chinese, etc.)
• GCC might be built with option --with-gcc-major-version-only. And some distros (e.g. Fedora) are already using that
• GCC might be built with option --with-pkgversion. And --version output will contain something like Android (5220042 based on r346389c) clang version 8.0.7 (it's real version string)