详解程序意外中断自动重启shell脚本（以Python为例）

cd Desktop
vim run.sh #新建名为run的shell脚本

#!/bin/bash
while [ 1 ];do
 python run.py
done

chmod 777 run.sh #设置shell脚本权限
./run.sh   #运行shell脚本

nohup ./run5.py &

import os
class UrlManager(object):
 def __init__(self):						#建立两个数组的文件
  with open('new_urls.txt','r+') as new_urls:
   self.new_urls = new_urls.read()
  with open('old_urls.txt','r+') as old_urls:
   self.old_urls = old_urls.read()

 def add_new_url(self, url): 				 #添加url到new_ulrs文件中
  if url is None:
   return
  if url not in self.new_urls and url not in self.old_urls:
   with open('new_urls.txt', 'a') as new_urls:
    new_urls.write(url)
  else:
   print('url had done')

 def add_new_urls(self, urls):				#添加多个url到new_ulrs文件中
  # if urls is None or (len(url) == 0 for url in urls):
  if urls is None:
   print('url is none')
   return
  for url in urls:
   if urls is None:
    print('url is none')
    return
   else:
    self.add_new_url(url)

 def has_new_url(self):
  return len(self.new_urls) != 0

 def get_new_url(self):				
  new_url = get_last_line('new_urls.txt') 	#读取new_urls文件中最后一个url
  del_last_url('new_urls.txt',new_url)		#删除new_urls文件中最后一个url
  add_old_urls('old_urls.txt',new_url)		#将读取出来的url添加入old_urls数组中
  return new_url

	def get_last_line(inputfile):
	 filesize = os.path.getsize(inputfile)
	 blocksize = 1024
	 dat_file = open(inputfile, 'rb')
	
	 last_line = b""
	 lines = []
	 if filesize > blocksize:
	  maxseekpoint = (filesize // blocksize) # 这里的除法取的是floor
	  maxseekpoint -= 1
	  dat_file.seek(maxseekpoint * blocksize)
	  lines = dat_file.readlines()
	  while ((len(lines) < 2) | ((len(lines) >= 2) & (lines[1] == b'\r\n'))): # 因为在Windows下，所以是b'\r\n'
	   # 如果列表长度小于2，或者虽然长度大于等于2，但第二个元素却还是空行
	   # 如果跳出循环，那么lines长度大于等于2，且第二个元素肯定是完整的行
	   maxseekpoint -= 1
	   dat_file.seek(maxseekpoint * blocksize)
	   lines = dat_file.readlines()
	 elif filesize: # 文件大小不为空
	  dat_file.seek(0, 0)
	  lines = dat_file.readlines()
	 if lines: # 列表不为空
	  for i in range(len(lines) - 1, -1, -1):
	   last_line = lines[i].strip()
	   if (last_line != b''):
	    break # 已经找到最后一个不是空行的
	 dat_file.close()
	 return last_line
	
	def del_last_url(fname,part):
	 with open(fname,'rb+') as f:
	  a = f.read()
	 a = a.replace(part,b'')
	 with open(fname,'wb+') as f:
	  f.write(a)
	  
	def add_old_urls(fname,new_url):
	 line = new_url + b'\r'
	 with open(fname,'ab') as f:
	  f.write(line)