☩ Walking in Light with Christ – Faith, Computing, Diary

Sometimes it happens that you end up on your server with a multiple of empty files. The reason for that could be different for example it could be /tmp is overflown with some session store files on a busy website, or due to some programmers Web executed badly written PHP / Python / Perl / Ruby code bug or lets say Content Management System ( CMS ) based website based on WordPress / Joomla / Drupal / Magento / Shopify etc. due to a broken plugin some specific directory could get filled up with plenty of meaningless empty files, that never gets wiped out if you don't care. This could happen if you offer your users to share files online to a public sharing service as WebFTP and some of the local hacked UNIX user accounts decides to make you look like a fool and run an endless loop to create files in your Hard Drive until your small server HDD filesystem of few terabytes gets filled up with useless empty files and due to full inode count on the filesystem your machine running running services gets disfunctional …

Hence on servers with shared users or simply webservers it is always a good idea to keep an eye on filesystem used nodes count by system are and in case if notices a sudden increase of used FS inodes as part of the investigation process on what caused it to check the amount of empty files on the system attached SCSI / SSD / SAS whatever drive.
 

1. Show a list of free inodes on server

Getting inodes count after logged is done with df command

root@linux-server:~# df -i
Filesystem        Inodes   IUsed     IFree IUse% Mounted on
udev             2041464     516   2040948    1% /dev
tmpfs            2046343    1000   2045343    1% /run
/dev/sdb2       14655488 1794109  12861379   13% /
tmpfs            2046343       4   2046339    1% /dev/shm
tmpfs            2046343       8   2046335    1% /run/lock
tmpfs            2046343      17   2046326    1% /sys/fs/cgroup
/dev/sdc6        6111232  6111232   0   100% /var/www
/dev/sda1       30162944 3734710  26428234   13% /mnt/sda1
/dev/sdd1      122093568 8011342 114082226    7% /backups
tmpfs            2046343      13   2046330    1% /run/user/1000

2. Show all empty files and directories count

### count empty directories ### root@linux-server:~# find /path/ -empty -type d | wc -l

### count empty files only ### root@linux-server:~# find /path/ -empty -type f | wc -l

3. List all empty files in directory or root dir

As you can see on the server in above example the amount of inodes of empty inodes is depleted.
The next step is to anylize what is happening in that web directory and if there is a multitude of empty files taking up all our disk space.
 

root@linux-server:~# find /var/www -type f -empty > /root/empty_files_list.txt

As you can see I'm redirecting output to a file as with the case of many empty files, I'll have to wait for ages and console will get filled up with a data I'll be unable to easily analyze …

If the problem is another directory in your case, lets say the root dir.

root@linux-server:~#  DIR='/';
root@linux-server:~# find $DIR -type f -empty > /root/empty_files_list.txt

4. Getting empty directories list

Under some case it might be that the server is overflowed with empty directories. This is also a thing some malicious cracker guy could do to your server if he can't root the server with some exploit but wants to bug you and 'show off his script kiddie 3l337 magic tricks' :). This is easily done with a perl / python or bash shell endless loop inside which a random file named millions of empty directories instead of files is created.

To look up for empty directories hence use:

root@linux-server:~# DIR='/home';
root@linux-server:~# find  $DIR . -type d -empty > /root/empty_directories_list.txt

5. Delete all empty files only to clean up inodes

Deletion of empty files will automatically free up the inodes occupied, to delete them.

root@linux-server:~# cd /path/containing/multiple/empty-dirs/
root@linux-server:~# find . -type f -empty -exec rm -fr {} \;

6. Delete all empty directories only to clean up inocommanddes

root@linux-server:~# find . -type d -empty -exec rm -fr {} \;

7. Delete all empty files and directories to clean up inodes

root@linux-server:~# cd /path/containing/multiple/empty-dirs/
root@linux-server:~# find . -empty -delete

8. Use find + xargs to delete if files count to delete is too high

root@linux-server:~# find . -empty | xargs rm -r

That's all folks ! Enjoy now your Filesystem to have retrieved back the lost inodes from the jump empty files or directories.

Happy cleaning  🙂