Find/Remove oldest file in directory

Question

I am trying to delete oldest file in directory when number of files reaches a threshold.

list_of_files = os.listdir('log')    

if len([name for name in list_of_files]) == 25:
    oldest_file = min(list_of_files, key=os.path.getctime)
    os.remove('log/'+oldest_file)

Problem: The issue is in min method. list_of_files does not contain full path, so it is trying to search file in current directory and failing. How can I pass directory name ('log') to min()?

Have you looked at `os.path.abspath`? And errr, isn't this what facilities such as logrotate are for? — Jon Clements, Dec 10 '17 at 13:25
`sorted(os.listdir(path), key=os.path.getctime)[0]` gives you the oldest file. — srikavineehari, Dec 10 '17 at 13:26
@srig that's not the issue here, and using `min()` over the list instead is efficient of sorting the entire list to take the first is rather inefficient — Jon Clements, Dec 10 '17 at 13:29
Thanks for pointing to logrotate.. new at python.. gonna look at it.. but its good if I could understand what's wrong here.. — cosmos, Dec 10 '17 at 13:31
adding os.path.abspath in key gives this error AttributeError: 'function' object has no attribute 'getctime' — cosmos, Dec 10 '17 at 13:32
@user2407394 apply `os.path.abspath` to `oldest_file` - then `os.remove` that - is that what you're doing? — Jon Clements, Dec 10 '17 at 13:38
Sorry I didn't get.. Its failing at min() because list_of_files does not contain full path.. where can I add os.path.abspath to oldest_file? — cosmos, Dec 10 '17 at 13:49

score 17 · Accepted Answer · edited Apr 02 '20 at 01:14

17

list_of_files = os.listdir('log')
full_path = ["log/{0}".format(x) for x in list_of_files]

if len(list_of_files) == 25:
    oldest_file = min(full_path, key=os.path.getctime)
    os.remove(oldest_file)

edited Apr 02 '20 at 01:14

MetaStack

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answered Dec 10 '17 at 13:39

Martin

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This'll work if the listdir and the log file are in the *same* place - it's better to (generally and to not repeat the use of where the file comes from) use the `os.path.abspath` to retrieve the full path name of the file and then `os.remove` that – Jon Clements Dec 10 '17 at 13:40

score 6 · Answer 2 · answered Dec 10 '17 at 13:49

os.listdir will return relative paths - those are ones that are relative to your current/present working directory/context of what your Python script was executed in (you can see that via os.getcwd()).

Now, the os.remove function expects a full path/absolute path - shells/command line interfaces infer this and do it on your behalf - but Python doesn't. You can get that via using os.path.abspath, so you can change your code to be (and since os.listdir returns a list anyway, we don't need to add a list-comp over it to be able to check its length)...:

list_of_files = os.listdir('log')    

if len(list_of_files) >= 25:
    oldest_file = min(list_of_files, key=os.path.getctime)
    os.remove(os.path.abspath(oldest_file))

That keeps it generic as to where it came from - ie, whatever was produced in the result of os.listdir - you don't need to worry about prepending suitable file paths.

Actually, this was not the issue.. os.remove correctly takes relative path (python 3.7).. The problem is inside min().. list_of_files contains only file name "abc.log" but not the relative path "log/abc.com".. so min() is unable to find key.. — cosmos, Dec 10 '17 at 13:55
The script is being executed from parent directory of 'log' directory.. Perhaps I didn't phrase the question that way.. — cosmos, Dec 10 '17 at 13:57

score 4 · Answer 3 · edited Mar 14 '20 at 15:21

I was trying to achieve the same as what you are trying to achieve. and was facing a similar issue related to os.path.abspath() I am using a windows system with python 3.7

and the issue is that os.path.abspath() gives one folder up location replace "Yourpath" and with the path of folder in which your file is and code should work fine

import os
import time

oldest_file = sorted([ "Yourpath"+f for f in os.listdir("Yourpath")], key=os.path.getctime)[0]

print (oldest_file)
os.remove(oldest_file)
print ("{0} has been deleted".format(oldest_file))`

There must be some cleaner method to do the same I'll update when I get it

score 3 · Answer 4 · answered Dec 27 '20 at 09:57

3

The glob library gives on the one hand full paths and allows filtering for file patterns. The above solution resulted in the directory itself as the oldest file, which is not that what I wanted. For me, the following is suitable (a blend of glob and the solution of @Ivan Motin)

import glob

sorted(glob.glob("/home/pi/Pictures/*.jpg"), key=os.path.getctime)[0]

answered Dec 27 '20 at 09:57

Thomas Bobek

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for me worked this: print (sorted(glob.glob("*.json"), key=os.path.getctime)[-1]) – Jakub Oct 11 '22 at 15:04

score 1 · Answer 5 · answered Jul 08 '19 at 19:48

1

using comprehension (sorry, couldn't resist):

oldest_file = sorted([os.path.abspath(f) for f in os.listdir('log') ], key=os.path.getctime)[0]

answered Jul 08 '19 at 19:48

Ivan Motin

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Find/Remove oldest file in directory

5 Answers5