How would I create a file named . (dot) and read or write data to it, given that . also refers to the current directory?

I know this is possible because I have a directory structure. I'm looking at with ls --all -l that shows a file named . owned by a different user than the user that owns the . and .. directories.

  • 1
    Not possible, but you can create a file that appears as just "." to ls output. For example: touch ". ". You won't be able to tell the trailing space is there in ls output.
    – jordanm
    Sep 29 '18 at 4:18
  • 1
    Also, I would be very suspicious of a file named ". ", as dir names such as that is often used to hide malicious code.
    – jordanm
    Sep 29 '18 at 4:19
  • i don't want to execute it, just to find what's in it. It seems you are probably right that the file isn't actually named '.' but i can't figure out how to cat it. i basically want to escape the . and say something like .* i guess, but it's not working Sep 29 '18 at 4:20
  • What do you get with printf '%s\n' .* | sed -n l ?
    – ImHere
    Sep 29 '18 at 4:28
  • 3 lines: (.$\n .\\ \\ $\n ..$\n). \n denotes a newline in the output Sep 29 '18 at 4:28

I'm afraid it only looks like you have a file called .. What is very likely happening is that you have a file whose name starts with a dot but is then followed by a whitespace or other special character. To demonstrate how you'd figure this out:

$ cd "$(mktemp --directory)"
$ touch '. '
$ for path in .*
> do
>     printf '%s' "$path" | xxd
> done
00000000: 2e                                       .
00000000: 2e20                                     . 
00000000: 2e2e                                     ..

The dotfile (the second entry above) shows up as a dot (0x2e) followed by a space character (0x20).

  • Note that %q is not POSIX. Yes, it works in bash, (*)ksh, zsh (with similar but not identical results) but not in older POSIX shells.
    – ImHere
    Sep 29 '18 at 21:30

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