command 'x86_64-linux-gnu-gcc' failed with exit status 1错误及解决方案

　　Ubuntu16.04安装Scrapy（pip install Scrapy）时提示错误如下：

Failed building wheel for cryptography
  Running setup.py clean for cryptography
Failed to build cryptography

error: command 'x86_64-linux-gnu-gcc' failed with exit status 

    ----------------------------------------
Command "/usr/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-build-2wwgqS/cryptography/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-IPpc2q-record/install-record.txt --single-version-externally-managed --compile" failed with error code  in /tmp/pip-build-2wwgqS/cryptography/

解决办法，参考：http://stackoverflow.com/questions/22073516/failed-to-install-python-cryptography-package-with-pip-and-setup-py

On Windows

If you’re on Windows you’ll need to make sure you have OpenSSL installed. There are pre-compiled binaries available. If your installation is in an unusual location set the LIB and INCLUDE environment variables to include the corresponding locations. For example:

C:\> \path\to\vcvarsall.bat x86_amd64
C:\> set LIB=C:\OpenSSL-1.0.1f-64bit\lib;%LIB%
C:\> set INCLUDE=C:\OpenSSL-1.0.1f-64bit\include;%INCLUDE%
C:\> pip install cryptography

Building cryptography on Linux

cryptography should build very easily on Linux provided you have a C compiler, headers for Python (if you’re not using pypy), and headers for the OpenSSL and libffi libraries available on your system.

For Debian and Ubuntu, the following command will ensure that the required dependencies are installed:

sudo apt-get install build-essential libssl-dev libffi-dev python-dev

For Fedora and RHEL-derivatives, the following command will ensure that the required dependencies are installed:

sudo yum install gcc libffi-devel python-devel openssl-devel

You should now be able to build and install cryptography with the usual.

pip install cryptography