Read files in reverse till specific line (character) in Python

Question

I have a large log file. Every minute I add recent activity of the OS. It looks like:

#@#@#@#@#@#@#@ 
Time:12:00 PM, CPU:12.0,RAM:12334321,Network:1231231233,....
#@#@#@#@#@#@#@
Time:12:01 PM, CPU:14.0,RAM:12354621,Network:1239864833,....
#@#@#@#@#@#@#@
Time:12:02 PM, CPU:9.0,RAM:12398781,Network:1231598697,....
#@#@#@#@#@#@#@

I used "#@#@#@#@#@#@#@" as the separator. every time I open the file and write (add) the current status and then close it.

To calculate some of the parameters I need to know what was the last situation of the system, so I need to open the file and read the file in reverse until I reach the separator (#@#@#@#@#@#@#@). How can I read the file in reverse till specific character which in my case is the seperator (#@#@#@#@#@#@#@) and put it (the last records of OS) into a list or tuple.

Thanks!

Answer 1

import re
p = re.compile(r'#@#@#@#@#@#@#@(?!.*?#@#@#@#@#@#@#@)(.*)$', re.DOTALL)
test_str = "#@#@#@#@#@#@#@ \nTime:12:00 PM, CPU:12.0,RAM:12334321,Network:1231231233,....\n#@#@#@#@#@#@#@\nTime:12:01 PM, CPU:14.0,RAM:12354621,Network:1239864833,....\n#@#@#@#@#@#@#@\nTime:12:02 PM, CPU:9.0,RAM:12398781,Network:1231598697,....\n#@#@#@#@#@#@#@\nTime:12:02 PM, CPU:9.0,RAM:12398781,Network:1231598697,....\nasasdas\ndsa\nd\n\nasd"
re.findall(p, test_str)

Here instead of test_str you can use file.read().See demo.

http://regex101.com/r/yP3iB0/21

• pafpaf: The code run on my mac perfectly, but when i run it in windows i get this error: File "Gtest.py", line 2 p = re.compile(ur'#@#@#@#@#@#@#@(?!.*?#@#@#@#@#@#@#@)(.*)$', re.DOTALL) ^ SyntaxError: invalid syntax Press any key to continue . . .
• pafpaf: My bad ! Your code works with python v2, I need a code for python v3 ! sorry, I will mention it in my Question. again sorry.
• vks: @user3636424 this code will work in python3 as well.Just remove the u thing.Use the updated code
• jadkik94: You'd have to read the whole file in memory though. Isn't it better to keep a buffer of the last lines between two separators and keep reading until EOF?