Self-inflicted "abort" in a newbie attempt at read-only exploration of a cloned repository?

Self-inflicted "abort" in a newbie attempt at read-only exploration of a cloned repository?

[Thierry Moreau]

Dear GIT enthusiasts!

This ends up with a "git checkout" command aborting. A bit frustrating 
at the early stage of GIT learning curve.

My first goal is to clone repositories locally in order to explore the 
various linux kernel versions, with the rich GIT metadata.

Thus, I clone:

$  git clone --branch linux-4.16.y 
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git 
linux-stable
$  git -C linux-stable/ branch
* linux-4.16.y

So far so good. Then, I want to extract an earlier kernel version into a 
tmp dir:

$  mkdir tmp
$  git -C linux-stable/ --work-tree $PWD/tmp/ checkout linux-4.15.y
$  git -C linux-stable/ branch
* linux-4.15.y
   linux-4.16.y

I got my extracted 4.15 version but the source repository (index? ...?) 
has somehow changed. Let me try something silly:

$  git -C linux-stable/ --work-tree $PWD/tmp/ checkout linux-4.14.y
$  git -C linux-stable/ branch
* linux-4.14.y
   linux-4.15.y
   linux-4.16.y

I indeed switched my extracted version from 4.15 to 4.14, but I am 
puzzled that the local source repository (linux-stable) is modified. 
Then I try to bring it back closer to its original state, just to keep 
things tidy:

$  git -C linux-stable/ checkout linux-4.16.y

And this command aborts, both with Git versions 2.01 and 2.17. Here is 
the truncated command output:

error: Your local changes to the following files would be overwritten by 
checkout:
	.gitignore
	.mailmap
	Documentation/00-INDEX
	Documentation/ABI/obsolete/sysfs-gpio
	Documentation/ABI/stable/sysfs-bus-vmbus
	Documentation/ABI/stable/sysfs-devices
	[... ...]
	Documentation/devicetree/bindings/arm/mediatek/mediatek,vencsys.txt
	Documentation/devicetree/bindings/arm/omap/crossbar.txt
	Documentation/devicetree/bindings/arm/omap/ctrl.txt
	Documentation/devicetree/bindings/arm/realtek.txt
	Documentation/devicetree/bindings/arm/rock
error: The following untracked working tree files would be overwritten 
by checkout:
	Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Diagram.html
	Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.html
	Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-invocation.svg
	Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-registry.svg
	Documentation/RCU/Design/Memory-Ordering/TreeRCU-dyntick.svg
	[... ...]
	arch/riscv/include/asm/smp.h
	arch/riscv/include/asm/spinlock.h
	arch/riscv/include/asm/spinlock_types.h
	arch/riscv/include/asm/string.h
	arch/riscv/include/
Aborting

Questions:
=========

Is there a GIT tutorial that begins with my stated goal of an 
extract-only usage of cloned GIT repositories? (Maybe the root cause is 
my reluctance to learn the more involved GIT usages.)

Does the above reproducible abort deserve attention?

Any suggestion for my stated goal?

Thanks in advance,

- Thierry Moreau

Re: Self-inflicted "abort" in a newbie attempt at read-only exploration of a cloned repository?

[Bryan Turner]

On Thu, Apr 5, 2018 at 12:42 PM, Thierry Moreau
<thierry.moreau@connotech.com> wrote:
> Dear GIT enthusiasts!
>
> This ends up with a "git checkout" command aborting. A bit frustrating at
> the early stage of GIT learning curve.
>
> My first goal is to clone repositories locally in order to explore the
> various linux kernel versions, with the rich GIT metadata.
>
> Thus, I clone:
>
> $  git clone --branch linux-4.16.y
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
> linux-stable
> $  git -C linux-stable/ branch
> * linux-4.16.y
>
> So far so good. Then, I want to extract an earlier kernel version into a tmp
> dir:
>
> $  mkdir tmp
> $  git -C linux-stable/ --work-tree $PWD/tmp/ checkout linux-4.15.y
> $  git -C linux-stable/ branch
> * linux-4.15.y
>   linux-4.16.y

The documentation for --work-tree says:

--work-tree=<path>

Set the path to the working tree. It can be an absolute path or a path
relative to the current working directory. This can also be controlled
by setting the GIT_WORK_TREE environment variable and the
core.worktree configuration variable (see core.worktree in
git-config(1) for a more detailed discussion).

So passing --work-tree tells Git where to store your _files_, but it's
still using the same .git directory.

If your goal is to have worktrees for various versions, that implies
the git worktree [1] command might be more along the lines of what
you're looking for. An invocation based on above might look like this:
$ git -C linux-stable/ worktree add $PWD/tmp/ checkout linux-4.15.y

That should leave linux-4.16.y checked out in linux-stable, while
creating a full work tree in $PWD/tmp that has 4.15.y checked out.

Note that worktree is a newer git command. 2.17 has it, but old
versions like 2.1 won't.

[1] https://git-scm.com/docs/git-worktree

Hope this helps!
Bryan

Re: Self-inflicted "abort" in a newbie attempt at read-only exploration of a cloned repository?

[Bryan Turner]

On Thu, Apr 5, 2018 at 4:18 PM, Bryan Turner <bturner@atlassian.com> wrote:
> On Thu, Apr 5, 2018 at 12:42 PM, Thierry Moreau
> <thierry.moreau@connotech.com> wrote:
>> Dear GIT enthusiasts!
>>
>> This ends up with a "git checkout" command aborting. A bit frustrating at
>> the early stage of GIT learning curve.
>>
>> My first goal is to clone repositories locally in order to explore the
>> various linux kernel versions, with the rich GIT metadata.
>>
>> Thus, I clone:
>>
>> $  git clone --branch linux-4.16.y
>> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
>> linux-stable
>> $  git -C linux-stable/ branch
>> * linux-4.16.y
>>
>> So far so good. Then, I want to extract an earlier kernel version into a tmp
>> dir:
>>
>> $  mkdir tmp
>> $  git -C linux-stable/ --work-tree $PWD/tmp/ checkout linux-4.15.y
>> $  git -C linux-stable/ branch
>> * linux-4.15.y
>>   linux-4.16.y
>
> The documentation for --work-tree says:
>
> --work-tree=<path>
>
> Set the path to the working tree. It can be an absolute path or a path
> relative to the current working directory. This can also be controlled
> by setting the GIT_WORK_TREE environment variable and the
> core.worktree configuration variable (see core.worktree in
> git-config(1) for a more detailed discussion).
>
> So passing --work-tree tells Git where to store your _files_, but it's
> still using the same .git directory.
>
> If your goal is to have worktrees for various versions, that implies
> the git worktree [1] command might be more along the lines of what
> you're looking for. An invocation based on above might look like this:
> $ git -C linux-stable/ worktree add $PWD/tmp/ checkout linux-4.15.y

Apologies, I didn't mean to have the "checkout" in that.
$ git -C linux-stable/ worktree add $PWD/tmp/ linux-4.15.y

>
> That should leave linux-4.16.y checked out in linux-stable, while
> creating a full work tree in $PWD/tmp that has 4.15.y checked out.
>
> Note that worktree is a newer git command. 2.17 has it, but old
> versions like 2.1 won't.
>
> [1] https://git-scm.com/docs/git-worktree
>
> Hope this helps!
> Bryan

Re: Self-inflicted "abort" in a newbie attempt at read-only exploration of a cloned repository?

[Thierry Moreau]

On 05/04/18 11:34 PM, Bryan Turner wrote:
> On Thu, Apr 5, 2018 at 4:18 PM, Bryan Turner <bturner@atlassian.com> wrote:
>>
>> So passing --work-tree tells Git where to store your _files_, but it's
>> still using the same .git directory.
>>
>> If your goal is to have worktrees for various versions, that implies
>> the git worktree [1] command might be more along the lines of what
>> you're looking for. An invocation based on above might look like this:
>> $ git -C linux-stable/ worktree add $PWD/tmp/ checkout linux-4.15.y
>
> Apologies, I didn't mean to have the "checkout" in that.
> $ git -C linux-stable/ worktree add $PWD/tmp/ linux-4.15.y
>
>>
>> That should leave linux-4.16.y checked out in linux-stable, while
>> creating a full work tree in $PWD/tmp that has 4.15.y checked out.
>>
>> Note that worktree is a newer git command. 2.17 has it, but old
>> versions like 2.1 won't.
>>
>> [1] https://git-scm.com/docs/git-worktree
>>
>> Hope this helps!

For sure, it helps! Thanks.

- Thierry

Re: Self-inflicted "abort" in a newbie attempt at read-only exploration of a cloned repository?

[Jeff King]

On Thu, Apr 05, 2018 at 04:18:23PM -0700, Bryan Turner wrote:

> The documentation for --work-tree says:
> 
> --work-tree=<path>
> 
> Set the path to the working tree. It can be an absolute path or a path
> relative to the current working directory. This can also be controlled
> by setting the GIT_WORK_TREE environment variable and the
> core.worktree configuration variable (see core.worktree in
> git-config(1) for a more detailed discussion).
> 
> So passing --work-tree tells Git where to store your _files_, but it's
> still using the same .git directory.
> 
> If your goal is to have worktrees for various versions, that implies
> the git worktree [1] command might be more along the lines of what
> you're looking for. An invocation based on above might look like this:
> $ git -C linux-stable/ worktree add $PWD/tmp/ checkout linux-4.15.y

Everything you've said here is completely accurate. But the original
report does make me wonder if we've set up users for failure by
overloading the term "worktree". Clearly it means two very different
things in:

  git --work-tree=foo

and

  git worktree add foo

I'm not sure what to do about it at this point, though. :(

-Peff

Re: Self-inflicted "abort" in a newbie attempt at read-only exploration of a cloned repository?

[Thierry Moreau]

On 06/04/18 07:56 PM, Jeff King wrote:
> On Thu, Apr 05, 2018 at 04:18:23PM -0700, Bryan Turner wrote:
>
>> The documentation for --work-tree says:
>>
>> --work-tree=<path>
>>
>> Set the path to the working tree. It can be an absolute path or a path
>> relative to the current working directory. This can also be controlled
>> by setting the GIT_WORK_TREE environment variable and the
>> core.worktree configuration variable (see core.worktree in
>> git-config(1) for a more detailed discussion).
>>
>> So passing --work-tree tells Git where to store your _files_, but it's
>> still using the same .git directory.
>>
>> If your goal is to have worktrees for various versions, that implies
>> the git worktree [1] command might be more along the lines of what
>> you're looking for. An invocation based on above might look like this:
>> $ git -C linux-stable/ worktree add $PWD/tmp/ checkout linux-4.15.y
>
> Everything you've said here is completely accurate. But the original
> report does make me wonder if we've set up users for failure by
> overloading the term "worktree". Clearly it means two very different
> things in:
>
>    git --work-tree=foo
>
> and
>
>    git worktree add foo
>
> I'm not sure what to do about it at this point, though. :(
>

The documentation for 'git worktree add' was adequate for my problem 
solving process. My difficulty occurred because I used an earlier GIT 
version. The terminology overloading might not be a big issue.

Regards,

- Thierry