g++-5.2.0 -v -m32 -dynamiclib ./tmp2.o -o ./tmp2.so

gistfile1.txt

lvm@LvMsUbuntu:~/Documents/MyFirstDylib$ g++-5.2.0 -v -m32 -dynamiclib ./tmp2.o -o ./tmp2.so
Using built-in specs.
COLLECT_GCC=g++-5.2.0
COLLECT_LTO_WRAPPER=/usr/local/lvm/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/5.2.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../configure --prefix=/usr/local/lvm/gcc-5.2.0 --enable-checking=release --with-gmp=/usr/local/lvm/gmp-6.0.0 --with-mpfr=/usr/local/lvm/mpfr-3.1.2 --with-mpc=/usr/local/lvm/mpc-1.0.3 --enable-languages=c,c++,fortran,objc,obj-c++ --with-isl=/usr/local/lvm/isl-0.14 --with-cloog=/usr/local/lvm/cloog-0.18.4 --program-suffix=-5.2.0
Thread model: posix
gcc version 5.2.0 (GCC) 
COMPILER_PATH=/usr/local/lvm/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/5.2.0/:/usr/local/lvm/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/5.2.0/:/usr/local/lvm/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/:/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/:/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/
LIBRARY_PATH=/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/32/:/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/../../../../lib32/:/lib/i386-linux-gnu/:/lib/../lib32/:/usr/lib/i386-linux-gnu/:/usr/lib/../lib32/:/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/:/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/../../../:/lib/i386-linux-gnu/:/lib/:/usr/lib/i386-linux-gnu/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-m32' '-dynamiclib' '-o' './tmp2.so' '-shared-libgcc' '-mtune=generic' '-march=x86-64'
 /usr/local/lvm/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/5.2.0/collect2 -plugin /usr/local/lvm/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/5.2.0/liblto_plugin.so -plugin-opt=/usr/local/lvm/gcc-5.2.0/libexec/gcc/x86_64-unknown-linux-gnu/5.2.0/lto-wrapper -plugin-opt=-fresolution=/tmp/cc896Htr.res -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lgcc --eh-frame-hdr -m elf_i386 -dynamic-linker /lib/ld-linux.so.2 -o ./tmp2.so /usr/lib/../lib32/crt1.o /usr/lib/../lib32/crti.o /usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/32/crtbegin.o -L/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/32 -L/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/../../../../lib32 -L/lib/i386-linux-gnu -L/lib/../lib32 -L/usr/lib/i386-linux-gnu -L/usr/lib/../lib32 -L/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0 -L/usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/../../.. -L/lib/i386-linux-gnu -L/usr/lib/i386-linux-gnu ./tmp2.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/local/lvm/gcc-5.2.0/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/32/crtend.o /usr/lib/../lib32/crtn.o
/usr/lib/../lib32/crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: error: ld returned 1 exit status