How to handle changed user ID

How to handle changed user ID

[Thomas Wolff]

I had to delete a corrupted Windows account and recreate it.
For cygwin, the new account, although with the same name, has a
different user id.
Of course, this creates access problems for existing files (even if they
appear to have the same user in ls -l, because the *old user* is still
listed in /etc/passwd).
Is there a canonical solution to this problem, other than running chown
-R $USER ~ ?
Can the new user be forced to use the previous user ID?
Thanks
Thomas

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Re: How to handle changed user ID

[cyg Simple]

On 12/7/2017 2:50 AM, Thomas Wolff wrote:
> I had to delete a corrupted Windows account and recreate it.
> For cygwin, the new account, although with the same name, has a
> different user id.
> Of course, this creates access problems for existing files (even if they
> appear to have the same user in ls -l, because the *old user* is still
> listed in /etc/passwd).
> Is there a canonical solution to this problem, other than running chown
> -R $USER ~ ?
> Can the new user be forced to use the previous user ID?

What happens if you simply remove /etc/passwd and /etc/group files?  A
change long ago caused these files to not be needed.

You may need to take ownership of the directories and their files at the
Windows system level.

-- 
cyg Simple

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Re: How to handle changed user ID

[Corinna Vinschen]

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On Dec  7 09:12, cyg Simple wrote:
> On 12/7/2017 2:50 AM, Thomas Wolff wrote:
> > I had to delete a corrupted Windows account and recreate it.
> > For cygwin, the new account, although with the same name, has a
> > different user id.
> > Of course, this creates access problems for existing files (even if they
> > appear to have the same user in ls -l, because the *old user* is still
> > listed in /etc/passwd).
> > Is there a canonical solution to this problem, other than running chown
> > -R $USER ~ ?
> > Can the new user be forced to use the previous user ID?
> 
> What happens if you simply remove /etc/passwd and /etc/group files?  A
> change long ago caused these files to not be needed.
> 
> You may need to take ownership of the directories and their files at the
> Windows system level.

Definitely, and this is independent of Cygwin.  The files have been
created with the Windows SID of the old user and thus the ownership
is still set to the old user.  Either taking ownership in Windows,
or starting a shell as admin and using chown -R (or more intelligent
variations using find) should do it.


Corinna

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Re: How to handle changed user ID

[Brian Inglis]

On 2017-12-07 00:50, Thomas Wolff wrote:
> I had to delete a corrupted Windows account and recreate it.
> For cygwin, the new account, although with the same name, has a different
> user id.

That id is the Cygwin hash of the Windows user id registry key; compare entries
from:
	$ getent passwd ; mkpasswd

> Of course, this creates access problems for existing files (even if they 
> appear to have the same user in ls -l, because the *old user* is still listed
> in /etc/passwd).

And should be shown if you use:
	$ ls -n ...
> Is there a canonical solution to this problem, other than running 
> chown -R $USER ~ ?
> Can the new user be forced to use the previous user ID?

Have you changed all file ownerships in Windows?

Have you tried renaming your id files out of the way so that Cygwin uses SAM/AD?
	$ mv /etc/passwd{,.save} ; mv /etc/group{,.save}
I did that a couple of years ago and had no problems since.
If you uncommented any lines or made any changes to /etc/nsswitch.conf, comment
them out again, if they affect .

If that doesn't work, rename the originals out of the way, as above, and run:
	$ mkpasswd > /etc/passwd ; mkgroup > /etc/group.

-- 
Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada

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Re: How to handle changed user ID

[Achim Gratz]

Thomas Wolff writes:
> Is there a canonical solution to this problem, other than running chown
> -R $USER ~ ?

Be careful with any recursive option, it can descend into paths you
really don't want it to go.  If what you need to do is any more
difficult than just taking ownership using the new SID, I can recommend
a program called "subinacl", it's a download from Microsoft.

> Can the new user be forced to use the previous user ID?

Not that I know of, no.  A SID will never be reused.

Achim.
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