error when trying to get the newest created directory in python

Question

I want to get the newest created directory. I followed this post. but I get errors when I tried it.

Here is my directory listing

    ls backups
    BACKUPSET_2016-01-14_11-26_.zip  DIFF-2016-01-17_00-00  DIFF-2016-01-20_00-00
    BACKUPSET_2016-01-14_11-28_.zip  DIFF-2016-01-18_00-00  DIFF-2016-01-21_00-00
    DIFF-2016-01-16_00-00            DIFF-2016-01-19_00-00  FULL-2016-01-14_14-11

I want to get the newest created file that starts with "DIFF"

Here is what I tried.

def get_latest_directory():
   all_dirs = [d for d in os.listdir('backups') if (os.path.isdir(d) and d.startswith('DIFF'))]
   print sorted(all_dirs, key=lambda x: os.path.getctime(x), reverse=True)[0]

if __name__=="__main__":
   get_latest_directory()

when I run this script, I get

./backup.py 
Traceback (most recent call last):
  File "./backup.py", line 33, in <module>
    get_latest_directory()
  File "./backup.py", line 19, in get_latest_directory
    print sorted(all_dirs, key=lambda x: os.path.getctime(x), reverse=True)[0]
IndexError: list index out of range

I made a small change in function above

def get_latest_directory():
   all_dirs = [d for d in os.listdir('backups')]
   print sorted(all_dirs, key=lambda x: os.path.getctime(x), reverse=True)[0]

now I get:

Traceback (most recent call last):
  File "./backup.py", line 34, in <module>
    get_latest_directory()
  File "./backup.py", line 20, in get_latest_directory
    print sorted(all_dirs, key=lambda x: os.path.getctime(x), reverse=True)[0]
  File "./backup.py", line 20, in <lambda>
    print sorted(all_dirs, key=lambda x: os.path.getctime(x), reverse=True)[0]
  File "/usr/lib64/python2.7/genericpath.py", line 64, in getctime
    return os.stat(filename).st_ctime
OSError: [Errno 2] No such file or directory: 'FULL-2016-01-14_14-11'

This does not make sense since I see this directory 'FULL-2016-01-14_14-11' when i execute the ls command.

what I am doing wrong. I am unable to figure out.

Thanks

My guess is that you need the full path name. `listdir` doesn't give the full path — SirParselot, Jan 21 '16 at 19:29
You need`os.path.join` but I don't know why you don't use glob as it is also used in the linked question — Padraic Cunningham, Jan 21 '16 at 19:39

SirParselot · Accepted Answer · 2016-01-21T19:40:21.017

2

You need the full path name so just add it to d in your list comprehension

def get_latest_directory():
    path_to_backups = 'path/to/backups/'
    all_dirs = [path_to_backsups + d for d in os.listdir(path_to_backups) if (os.path.isdir(path_to_backups + d) and d.startswith('DIFF'))]
    print sorted(all_dirs, key=lambda x: os.path.getctime(x), reverse=True)[0]

if __name__=="__main__":
   get_latest_directory()

edited Jan 21 '16 at 19:40

answered Jan 21 '16 at 19:32

SirParselot

2,640
2
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It fails the same for `all_dirs = [d for d in os.listdir('backups') if (os.path.isdir(d) and d.startswith('DIFF'))]` – brain storm Jan 21 '16 at 19:35
1

@brainstorm Sorry my original answer I thought you had fixed your list comprehension but looking at it closer I realized that you where still missing the full path. That would cause the `os.path.isdir(d)` to fail which would cause `all_dirs` to be empty – SirParselot Jan 21 '16 at 19:41

score 0 · Answer 2 · answered Jan 21 '16 at 19:35

0

As SirParselot describes, you need the full path while os.listdir() just gives you the relative path. To fix this, use os.path.abspath(), which maps relative paths to absolute paths.

[os.path.abspath(d) for d in os.listdir('backups') if (...)]

answered Jan 21 '16 at 19:35

Eli Rose

6,788
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`os.path.abspath(d)` will give you the full path to the directory you are in which isn't necessarily the path you want – SirParselot Jan 21 '16 at 19:47

error when trying to get the newest created directory in python

2 Answers2