Re: [Bug-tar] maybe need for clarification: --unlink-first vs. default operation when extracting files

[Sergey Poznyakoff]

Helmut Waitzmann <address@hidden> wrote:

> I guess, that tar removes a file which is to be replaced by an archive
> member before extracting, right?

Right.
 
> So, what's the purpose of the '--unlink-first' option?  What does
> "unconditionally" mean in this context?

The default operation is:

 1. Try to create file name to be extracted.
 2. If open fails because the file exists - remove the file.
 3. Create the new file.

The operation with --unlink-first is:

 1. Unlink the file first.
 2. Create the new file.

So, two steps, instead of three. Thus, --unlink-first can speed up
extracting of large archives.

Regards,
Sergey