Unix tools: what if a file is named minus something?

Question

I'm always wondering: most GNU/Unix tools take options in the form "minus something", sometimes followed by an argument. What if you got a file named minus something?

$ ls
-f
$ rm -f
$ ls
-f
$ mv -f abc
mv: missing destination file operand after `abc'
Try `mv --help' for more information.
$ cat -f
cat: invalid option -- 'f'
Try `cat --help' for more information.

or

$ ls
-ohello.c
$ gcc -ohello -ohello.c
gcc: fatal error: no input files
compilation terminated.

This is just out of curiosity; I don't have a use case for this.

Answer 1

To remove a file named -x, use rm -- -x (-- means end of options) or rm ./-x.

Answer 2

It is fairly common to ask this type of question in interview settings. A common way to handle files with dashes is either:

$ rm -- -f
$ rm ./-f

Answer 3

A common question in Unix. The main way is to give the full path name to the file, so it doesn't have a dash in front of it:

$ rm -file.txt
unknown option -l

$ rm ./-file.txt    #No problem!
$ rm $PWD/-file.txt #Same thing

Some commands, you can use a dash by itself (or a double dash) to end the options. However, this is not necessarily true with all commands, or even the same command on different systems.

$ rm -- -file.txt   #Works on Linux but not on some Unix systems

Answer 4

you have to use

  rm -- <filename>

Ex:

  rm -- -f