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将目录添加到 PYTHONPATH 会导致我的主目录也被添加

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将目录添加到 PYTHONPATH 会导致我的主目录也被添加

我尝试/home/myname/bin通过将以下内容插入到我的目录中来添加到我的 PYTHONPATH 中.bashrc：

if [ -d ~/bin ]; then
    export PYTHONPATH=$PYTHONPATH:/home/myname/bin
fi

不幸的是，这似乎将我的主目录添加到了 Python 的搜索路径中，如在 Python 中运行以下命令所示：

>>> import sys
>>> sys.path

['', '/home/myname', '/home/myname/bin', '/usr/lib/python3.4', '/usr/lib/python3.4/plat-x86_64-linux-gnu', '/usr/lib/python3.4/lib-dynload', '/usr/local/lib/python3.4/dist-packages', '/usr/lib/python3/dist-packages']

请注意，echo $PYTHONPATH只是返回:/home/myname/bin。

答案1

问题在于您包含了 的现有值PYTHONPATH。但是，该变量未设置，因此其计算结果为空字符串。出于某种原因，这似乎包括了python您的$HOME目录。据推测，这是默认目录：

$ python -c 'import sys; print sys.path'
['', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PILcompat', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.7', '/usr/lib/python2.7/dist-packages/wx-3.0-gtk2']

但是，如果我设置PYTHONPATH为空字符串，则$HOME包含 my：

$ PYTHONPATH=""; python -c 'import sys; print sys.path'
['', '/home/terdon', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PILcompat', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.7', '/usr/lib/python2.7/dist-packages/wx-3.0-gtk2']

PYTHONPATH因此，当您在设置时包含当前值时，您将获得以下行为：

$ PYTHONPATH="$PYTHONPATH:$HOME/bin" python -c 'import sys; print sys.path'
['', '/home/terdon', '/home/terdon/bin', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PILcompat', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.7', '/usr/lib/python2.7/dist-packages/wx-3.0-gtk2']

正确的设置方法是仅提供您想要添加的目录：

$ PYTHONPATH="$HOME/bin" python -c 'import sys; print sys.path'
['', '/home/terdon/bin', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-x86_64-linux-gnu', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PILcompat', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/pymodules/python2.7', '/usr/lib/python2.7/dist-packages/wx-3.0-gtk2']

或者，为了安全起见，万一定义了它，请检查它是否为空并采取相应措施：

if [ -d ~/bin ]; then
    [ -z "$PYTHONPATH" ] && 
        export PYTHONPATH="/home/myname/bin" ||
        export PYTHONPATH="$PYTHONPATH:/home/myname/bin"
fi

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