What does ./ mean?

Question

I'm having a hard time getting what ./ does.

In the Linux Essentials books, it asks me in an exercise to delete a file named -file. After googling, I found that I need to do rm ./-file but I don't get why!

Answer 1

The . directory is the current directory. The directory .. is the upper level of that directory

$ pwd
/home/user

$ cd docs; pwd   # change to directory 'docs'
/home/user/docs

$ cd .  ; pwd     # we change to the '.' directory, therefore we'll stay. No change
/home/user/docs

$ cd .. ; pwd     # back to up level
/home/user

In Linux, commands options are introduced by the - sign, i.e., ls -l, so if you want to make any reference to a file beginning with - such as -file, the command would think you are trying to specify an option. For example, if you want to remove it:

rm -file

will complain because it's trying to use the option file of the command rm. In this case you need to indicate where the file is. Being in the current directory, thus the . directory, you need to refer to that file as ./-file, meaning, in the directory ., the file -file. In this case the command rm won't think that's an option.

rm ./-file

It can be done, also, using --.

From man rm:

To remove a file whose name starts with a '-', for example '-foo', use one of these commands:

rm -- -foo
rm ./-foo

Answer 2

If you type rm -file you will be passing a commandline option to rm not the name -file.

To delete -file pass rm the name in quotes rm "-file" or escape the -. rm \\-file. In either bash or zsh if you are unsure that a command is getting the proper filename use tab completion. Examples: type rm -fiTAB if the screen does not printout rm -file you know you did something wrong and should fix it before hitting return, another example rm "-fiTAB should printout rm "-file".

As for ./, / is just the separator between directories and filenames. "." means present directory. ".." means the directory one up. So to delete the file foo in the present directory type rm ./foo ( rm foo is OK too ) to delete the file one directory up type rm ../foo to delete the file in the directory bar which is contained in the directory above type rm ../bar/foo.

In this case ./ is put in front of -file so that the - character is not the first thing that rm sees because that would make it think you are using some option.

If you know a bit of DOS, rm -file would correspond to rm /file in DOS.

Answer 3

. is the current directory. So e.g. ls and ls . are synonymous. If you are in /etc the commands cat /etc/fstab/, cat ./fstab and cat fstab do the same thing.

rm ./-file is used because rm parses everything starting with - as command line options and not file names. For example ls -l does not try to show file named -l, but ls ./-l and ls /some/directory/-l do.