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Re: Generic creation of a symblic link
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Re: Generic creation of a symblic link


  • Subject: Re: Generic creation of a symblic link
  • From: Jim Luther <email@hidden>
  • Date: Thu, 11 Oct 2012 22:29:09 -0700

As several others said, you cannot rewrite a symbolic link file. If you call symlink(path1, path2) and path2 refers to an existing file, you'll just get a EEXISTS error.

If you're trying to replace the target of a symlink atomically so that there's always a symbolic link file at a certain path, rename(2) is your friend. You can create a new symbolic link file in a temporary location and then rename it over an existing symlink:

    err = symlink(new_location, temp_symlink_location);
    err = rename(temp_symlink_location, symlink_location);

That will work even if the file you're renaming over isn't a symbolic link file.

- Jim

On Oct 11, 2012, at 5:50 PM, James Bucanek <email@hidden> wrote:

> Jim Luther <mailto:email@hidden> wrote (Thursday, October 11, 2012 5:30 PM -0700):
>
>> symlink files are created in a single step by symlink(2). It's not a multi-step process in user-land code -- it's a single call into the kernel.
>
> Which also means the source for symlink is probably in the kernel somewhere...
>
> So, if I can't figure out a simple way of obtaining the symlink's data before creating it, then I should be able to call symlink() with an empty or placeholder string (i.e. ".") and then rewrite its content later.
>
> --
> James Bucanek
>


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