为什么python虚拟环境启动后依然使用全局的python和pip

Question

为什么在python虚拟环境启动后，依然使用的是全局的python而不是虚拟环境中的python？
启动虚拟环境的方法如下：

chris@chrisbarry:~/Python/flask$ source venv/bin/activate

启动后，发现python还是使用的全局的

(venv)chris@chrisbarry:~/Python/flask$ which python
/usr/bin/python

这种情况该怎么办呢，是哪里出了问题呢？谢谢

Answer 1

你可以看看 venv/bin/activate 文件
一般是和环境变量有关系 PYTHONPATH 或者 是 PATH 有关系

还有一种可能性是你创建虚拟环境的时候指定了某些参数，使用原有的 python

# This file must be used with "source bin/activate" *from bash*
# you cannot run it directly

deactivate () {
    unset pydoc

    # reset old environment variables
    if [ -n "${_OLD_VIRTUAL_PATH-}" ] ; then
        PATH="$_OLD_VIRTUAL_PATH"
        export PATH
        unset _OLD_VIRTUAL_PATH
    fi
    if [ -n "${_OLD_VIRTUAL_PYTHONHOME-}" ] ; then
        PYTHONHOME="$_OLD_VIRTUAL_PYTHONHOME"
        export PYTHONHOME
        unset _OLD_VIRTUAL_PYTHONHOME
    fi

    # This should detect bash and zsh, which have a hash command that must
    # be called to get it to forget past commands.  Without forgetting
    # past commands the $PATH changes we made may not be respected
    if [ -n "${BASH-}" -o -n "${ZSH_VERSION-}" ] ; then
        hash -r 2>/dev/null
    fi

    if [ -n "${_OLD_VIRTUAL_PS1-}" ] ; then
        PS1="$_OLD_VIRTUAL_PS1"
        export PS1
        unset _OLD_VIRTUAL_PS1
    fi

    unset VIRTUAL_ENV
    if [ ! "${1-}" = "nondestructive" ] ; then
    # Self destruct!
        unset -f deactivate
    fi
}

# unset irrelevant variables
deactivate nondestructive

VIRTUAL_ENV="/Users/caimaoy/test/test/auto_monitor/monitor"
export VIRTUAL_ENV

_OLD_VIRTUAL_PATH="$PATH"
PATH="$VIRTUAL_ENV/bin:$PATH"
export PATH

# unset PYTHONHOME if set
# this will fail if PYTHONHOME is set to the empty string (which is bad anyway)
# could use `if (set -u; : $PYTHONHOME) ;` in bash
if [ -n "${PYTHONHOME-}" ] ; then
    _OLD_VIRTUAL_PYTHONHOME="$PYTHONHOME"
    unset PYTHONHOME
fi

if [ -z "${VIRTUAL_ENV_DISABLE_PROMPT-}" ] ; then
    _OLD_VIRTUAL_PS1="$PS1"
    if [ "x" != x ] ; then
        PS1="$PS1"
    else
    if [ "`basename \"$VIRTUAL_ENV\"`" = "__" ] ; then
        # special case for Aspen magic directories
        # see http://www.zetadev.com/software/aspen/
        PS1="[`basename \`dirname \"$VIRTUAL_ENV\"\``] $PS1"
    else
        PS1="(`basename \"$VIRTUAL_ENV\"`)$PS1"
    fi
    fi
    export PS1
fi

alias pydoc="python -m pydoc"

# This should detect bash and zsh, which have a hash command that must
# be called to get it to forget past commands.  Without forgetting
# past commands the $PATH changes we made may not be respected
if [ -n "${BASH-}" -o -n "${ZSH_VERSION-}" ] ; then
    hash -r 2>/dev/null
fi