Unix: Files starting with a dash, -

Ok, I have a bunch of files starting with a dash, -. Which is not so good... and I want to rename them. In my particular case I would just like to put a character in front of them.

I found the following line that should work, but because of it dash it doesn't:

for file in -N*.ext; do mv $file x$file; done

If I put an echo in front of the mv I get a bunch of

mv -N1.ext x-f1.ext
mv -N2.ext x-f2.ext

Which is correct, except of course it will think the first filename is options. So when I remove the echo and run it I just get a bunch of

mv: illegal option -- N

I have tried to change it to

for file in -N*.ext; do mv "$file" "x$file"; done

but the quotes are just ignored it seems. Tried to use single quotes, but then the variable wasn't expanded... What do I do here?

Update: I have now also tried to quote the quotes. Like this:

for file in -N*.ext; do mv '"'$file'"' '"'x$file'"'; done

And when I echo that, it looks correct, but when I actually run it I just get

mv: rename "-N1.ext" to "x-n1.ext":: No such file or directory

I have just no clue how to do this now... sigh

Svish

Posted 2010-03-15T10:39:23.993

Reputation: 27 731

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Answers

You need to use the keyword -- to tell the mv command that the arguments are not to be interpreted as options. Watch:

$ mv -N1.ext x-f1.ext
mv: invalid option -- N
Try `mv --help' for more information.

$ mv -- -N1.ext x-f1.ext
$ ls
x-f1.ext

Use -- after all the options on the commandline. Eg, if you're trying to use the -i option to mv, it would go before --:

mv -i -- -filename-begins-with-dash newfilename

quack quixote

Posted 2010-03-15T10:39:23.993

Reputation: 37 382

6Aaah. Didn't think about that one at all. In the mean time I found out I could stick ./ in front of the filename as well, which would work. But this is of course an even neater option :) – Svish – 2010-03-15T10:53:15.583

@Svish: that's fair, i didn't think about prepending the filename with ./ either. but you're correct, that works too, for this situation. – quack quixote – 2010-03-15T11:10:31.377

7Note that -- meaning don't process further arguments as options is a convention, and is not respected by all programs. Some use a lone - for that, and some don't accepting anything for that purpose. So prepending ./ is worth keeping in mind. – dmckee --- ex-moderator kitten – 2010-03-15T19:01:35.660

@dmckee is right; -- as a special argument is a GNU extension, but it is mentioned in the POSIX guidelines. see section 12.2, guideline 10: http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap12.html ... this means you can expect most POSIX and GNU utilities to respect the convention, but others may not.

– quack quixote – 2010-03-16T02:19:48.433

Another technique is to include the parent directory with the file name ...

To rename the file '-file-to-rename' to 'file-to-rename' ...

mv  ../parent-dir/-file-to-rename  file-to-rename

Thank You @Skippy le Grand Gourou. Confirmed that ./-file-to-rename works with mv and rm as in ...

mv  ./-file-to-rename  ./--file-to-rename

rm  ./-file-to-rename

DocSalvager

Posted 2010-03-15T10:39:23.993

Reputation: 310

1Or better, as already mentioned in comments to quack quixote's answer, using ./. – Skippy le Grand Gourou – 2014-01-19T18:09:07.323