Python os library basic practical exercise

1: Demand

In the v1.2020/7/20 big job project, it is hoped that every time a user sends a request on the front end, the back end will start a crawler to crawl the data into the database after receiving the request.
v2.2021/1/21 Record some pits encountered during automated operation and maintenance

2: Introduction to the os library

It was easy to use when working with papers before, but now I will do a systematic sorting and learning.
According to the official documentation of python3.8.1, this is a powerful built-in library that can manipulate files, execute command line statements, interact with the file system, and so on.

3：os.path

• abspath returns absolute path

os.path.abspath(path)

F:\Documentation\Courseware\ilfe 2020\iLife\code\backend\weibo-service\crawler\weiboSpider\setup.py

• basename returns the file name given the path

os.path.basename(path)

setup.py

• dirname returns the folder name given the path

os.path.dirname(path)

F:\Documentation\Courseware\ilfe 2020\iLife\code\backend\weibo-service\crawler\weiboSpider

• isfile/ isdir/ islink(path)Determine the type of path
• relpath returns path relative to the current folder

os.path.relpath(path, start=os.curdir)

• os.path.samefile(path1,path2) Determine whether the path is the same
• split distinguishes the prefix from the file name

Split the pathname path into a pair, (head, tail) where tail is the last pathname component and head is everything leading up to that. The tail part will never contain a slash; if path ends in a slash, tail will be empty. If there is no slash in path, head will be empty. If path is empty, both head and tail are empty.

4 Important functions in the os library

• chdir change working directory

os.chdir(path) 

For example, when executing the command of python -m module, you must go to the directory where the module is located

os.chdir('F:\\Documentation\\Courseware')
os.system('python -m weibo_spider');

Note that path is best to be an absolute path, otherwise it will be incorrect when executed from other places

• system executes command line statements

os.system(command) 

os.system('python -m weibo_spider');

Command is often written by concatenating strings, using';' to execute multiple statements

command="cd "+home_dir+"; ./ECCoordinator &> "+home_dir+"/output &"

It can also be used with subprocess.popen() to create a subprocess and execute the command

subprocess.Popen(['/bin/bash', '-c', command])

• getcwd Get the current path of the program

os.getcwd()