Errors when downloading emscripten - cmake

Question

I want to download emscripten on ubuntu 12.04.I downloaded Cmake 3.3.0 then I download esmscripten_portable and I run these commands:
# Fetch the latest registry of available tools.
./emsdk update
# Download and install the latest SDK tools.
./emsdk install latest
I got these error messages:
-- Could NOT find OCaml (missing: OCAMLFIND OCAML_VERSION OCAML_STDLIB_PATH)
-- Could NOT find OCaml (missing: OCAMLFIND OCAML_VERSION OCAML_STDLIB_PATH)
-- OCaml bindings disabled.
CMake Error at cmake/modules/HandleLLVMOptions.cmake:17 (message):
Host GCC version must be at least 4.7!
Call Stack (most recent call first):
CMakeLists.txt:378 (include)
-- Configuring incomplete, errors occurred!
See also "/home/slim/Bureau/emsdk_portable/clang/tag-e1.34.3/build_tag-e1.34.3_32/CMakeFiles/CMakeOutput.log".
See also "/home/slim/Bureau/emsdk_portable/clang/tag-e1.34.3/build_tag-e1.34.3_32/CMakeFiles/CMakeError.log".
CMake invocation failed due to exception!
Working directory: /home/slim/Bureau/emsdk_portable/clang/tag-e1.34.3/build_tag-e1.34.3_32
Command '['cmake', '-G', 'Unix Makefiles', '-DCMAKE_BUILD_TYPE=RelWithDebInfo', '-DPYTHON_EXECUTABLE=/usr/bin/python', '-DLLVM_TARGETS_TO_BUILD=X86;JSBackend', '-DLLVM_INCLUDE_EXAMPLES=OFF', '-DLLVM_INCLUDE_TESTS=OFF', '-DCLANG_INCLUDE_EXAMPLES=OFF', '-DCLANG_INCLUDE_TESTS=OFF', '/home/slim/Bureau/emsdk_portable/clang/tag-e1.34.3/src']' returned non-zero exit status 1
Installation failed!

Answer 1

I installed all these libraries very well but when I run this command:./emsdk activate latest.I got this message:The Emscripten configuration file /home/slim/.emscripten has been rewritten with the following contents:
import os
SPIDERMONKEY_ENGINE = ''
NODE_JS = 'node'
LLVM_ROOT='/home/slim/Bureau/emsdk_portable/clang/tag-e1.34.3/build_tag-e1.34.3_32/bin'
EMSCRIPTEN_ROOT='/home/slim/Bureau/emsdk_portable/emscripten/tag-1.34.3'
EMSCRIPTEN_NATIVE_OPTIMIZER='/home/slim/Bureau/emsdk_portable/emscripten/tag-1.34.3_32bit_optimizer/optimizer'
V8_ENGINE = ''
TEMP_DIR = '/tmp'
COMPILER_ENGINE = NODE_JS
JS_ENGINES = [NODE_JS]
To conveniently access the selected set of tools from the command line, consider adding the following directories to PATH, or call 'source ./emsdk_env.sh' to do this for you.
/home/slim/Bureau/emsdk_portable:/home/slim/Bureau/emsdk_portable/clang/tag-e1.34.3/build_tag-e1.34.3_32/bin:/home/slim/Bureau/emsdk_portable/emscripten/tag-1.34.3
I run :
source ./emsdk_env.sh
But when I run the command :
./emcc v
I got :
bash: ./emcc: No such file or directory