问题：
When running scripts in bash, I have to write ./ in the beginning:在 bash 中运行脚本时，我必须在开头写./ ：
$ ./manage.py syncdb
If I don't, I get an error message:如果我不这样做，我会收到一条错误消息：
$ manage.py syncdb
-bash: manage.py: command not found
What is the reason for this?这是什么原因？ I thought .我想. is an alias for current folder, and therefore these two calls should be equivalent.是当前文件夹的别名，因此这两个调用应该是等效的。
I also don't understand why I don't need ./ when running applications, such as:我也不明白为什么我在运行应用程序时不需要./ ，例如：
user:/home/user$ cd /usr/bin
user:/usr/bin$ git
(which runs without ./ ) （没有./运行）
解决方案：
参考一： https://en.stackoom.com/question/QZ07参考二： https://stackoom.com/question/QZ07