manage.py文件：
import os
import sys
if __name__ == "__main__":
print(__name__)#manage.py本身调用，那么会输出__main__
print(os.path.abspath(__file__))#输出当前文件的绝对路径
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mysite.settings")
#If key is in the dictionary, return its value. If not, insert key with a value of default and return default. default defaults to None.
print(os.environ.get('DJANGO_SETTINGS_MODULE'))#os.environ是个dict 输出mysite.settings
try:
from django.core.management import execute_from_command_line
except ImportError:
# The above import may fail for some other reason. Ensure that the
# issue is really that Django is missing to avoid masking other
# exceptions on Python 2.
try:
import django
except ImportError:
raise ImportError(
"Couldn't import Django. Are you sure it's installed and "
"available on your PYTHONPATH environment variable? Did you "
"forget to activate a virtual environment?"
)
raise
execute_from_command_line(sys.argv)
execute_from_command_line实际执行的是django/core/management/__init__.py中的ManagementUtility.execute方法
def execute_from_command_line(argv=None):
"""
A simple method that runs a ManagementUtility.
"""
utility = ManagementUtility(argv)
utility.execute()
class ManagementUtility(object):
"""
Encapsulates the logic of the django-admin and manage.py utilities.
A ManagementUtility has a number of commands, which can be manipulated
by editing the self.commands dictionary.
"""
def __init__(self, argv=None):
self.argv = argv or sys.argv[:]
self.prog_name = os.path.basename(self.argv[0])
self.settings_exception = None
def execute(self):
"""
Given the command-line arguments, this figures out which subcommand is
being run, creates a parser appropriate to that command, and runs it.
"""
try:
subcommand = self.argv[1]#获取第二个参数,比如mange.py startapp,那就是startapp
except IndexError:
subcommand = 'help' # Display help if no arguments were given.
os.environ.setdefault：任何一个djangoproject中的*.py文件都能够正常的使用项目中的数据模型操作
__name__：如果通过manage.py本身调用，那么print(name)输出可以看到等于main
Python中的name和main含义详解
