How to create a file named . on Linux easily. This is a very devious trick.

It is apparently possible to create a file named ., this will make the file unusable, but it is still very cool.

I used this simple command.

strace touch '.​'

Type a dot character “.”, then press Control-Shift-u and type 200b and then press ENTER, this will create a zero-width invisible character. Then press ENTER, this should create a file named “.”, this is useless as you cannot read the file, as it will point to the existing dot which is a directory.

┌──[jason@192.168.1.2]─[~/Documents/youtube-dl]
└──╼  ╼ $ ls -hula -i
total 12K
15739775 drwxrwxr-x  2 jason jason 4.0K Feb  3 09:18 .
15740070 -rw-rw-r--  1 jason jason    0 Feb  3 09:10 .​
14417975 drwxr-xr-x 36 jason jason 4.0K Feb  3 08:48 ..
15740053 -rwxrwxr-x  1 jason jason   14 Feb  3 09:03 my.sh

This is a very devious trick indeed, but it still could be deleted with the inode though. Its inode is 15740070, so you can delete it easily.

┌──[jason@192.168.1.2]─[~/Documents/youtube-dl]
└──╼  ╼ $ find . -inum 15740070 -exec rm -i {} \;
rm: remove regular empty file './.​'? y

But, this is only if the victim knows how to do this.

┌──[jason@192.168.1.2]─[~/Documents/youtube-dl]
└──╼  ╼ $ ls -hula -i
total 12K
15739775 drwxrwxr-x  2 jason jason 4.0K Feb  3 09:20 .
14417975 drwxr-xr-x 36 jason jason 4.0K Feb  3 08:48 ..
15740053 -rwxrwxr-x  1 jason jason   14 Feb  3 09:03 my.sh

Still, a very cool trick though, if it was a very large file it could be very annoying. The file still has an inode entry and this means it may still be deleted. But this still could be useful to someone out there.

On Windows, you can use this command in the command prompt window to create a folder that cannot really be deleted without advanced knowledge.

C:\Users\John\Desktop>md \\?\c:\users\John\Desktop\...

This is the folder I created.

C:\Users\John\Desktop>dir
 Volume in drive C has no label.
 Volume Serial Number is 2664-7B10
 
 Directory of C:\Users\John\Desktop
 
02/03/2021  12:20 PM    <DIR>          .
02/03/2021  12:20 PM    <DIR>          ..
02/03/2021  12:20 PM    <DIR>          ...

The … folder will contain all the files that the parent directory does. This is very strange. It must be a Windows NTFS filesystem bug.