Difference between revisions of "GIT Exercises"
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− | This page | + | This page has some exercises so you can experience different solutions/outcomes for a given task. |
− | By | + | By providing these (partly trivial) examples, the page ensures that you will not miss any of the scenarios while discovering the wonders of GIT. |
− | = Preface = | + | == Preface == |
− | Some of the examples are about how to deal with your work | + | Some of the examples are about how to deal with your work when other people are pushed in between. |
− | For this you need a 2nd clone. See setup. | + | For this you need a 2nd clone. See [[#Setup|setup]]. |
− | = Setup = | + | == Setup == |
The following steps should be performed before going to any of the below items. | The following steps should be performed before going to any of the below items. | ||
Line 17: | Line 17: | ||
;Second clone: | ;Second clone: | ||
− | To simulate what someone else would have done | + | To simulate what someone else would have done while you where working. |
This can use the same user, the effect will be the same. | This can use the same user, the effect will be the same. | ||
Line 25: | Line 25: | ||
git config user.name martin_2 | git config user.name martin_2 | ||
− | == Each example setup == | + | === Each example setup === |
In your first git folders, create a new branch | In your first git folders, create a new branch | ||
Line 35: | Line 35: | ||
git switch martins-test-1 | git switch martins-test-1 | ||
− | Thus both your folders are | + | Thus both your folders are at the same branch, and are up to date with the remote |
{{Note| In the example you work on "martins-test-1". But it is setup the same as your trunk branch would be. Therefore the same will apply when you work on trunk}} | {{Note| In the example you work on "martins-test-1". But it is setup the same as your trunk branch would be. Therefore the same will apply when you work on trunk}} | ||
− | = Pushing your commit, if someone else made changes | + | == Pushing your commit, if someone else made changes == |
− | |||
− | ;In Folder1 | + | {{Note| If you followed the configuration your "git pull" should be configured to default to either "--ff-ony" or "--rebase".<br/>The arguments given in to "pull" in the examples, will override the defaults |
+ | }} | ||
+ | |||
+ | === Rebase === | ||
+ | |||
+ | {| border=1 class="" style="text-align: left; border-collapse: collapse; padding: 10px; margin-left:10px;" | ||
+ | ! style="min-width: 60%; padding: 15px" | '''In Folder1''' | ||
+ | ! style="min-width: 30%; padding: 15px" | '''In Folder2 (other person)''' | ||
+ | |||
+ | |- | ||
+ | | colspan="2" style="padding-left: 50px;" | | ||
+ | Setup new branches [[#Each example setup]] | ||
+ | |||
+ | |- | ||
+ | || | ||
Edit the file lcl/forms.pp | Edit the file lcl/forms.pp | ||
git commit -m 'test changes' lcl/forms.pp | git commit -m 'test changes' lcl/forms.pp | ||
Line 50: | Line 63: | ||
* c739dd68a7 (origin/master, origin/HEAD) Revert "Test a change in forms" | * c739dd68a7 (origin/master, origin/HEAD) Revert "Test a change in forms" | ||
Your commit, follows the previous commit | Your commit, follows the previous commit | ||
+ | || | ||
− | + | |- | |
− | + | || | |
+ | || | ||
Edit the file ide/main.pp | Edit the file ide/main.pp | ||
git commit -m 'test other' ide/main.pp | git commit -m 'test other' ide/main.pp | ||
git push | git push | ||
− | + | |- | |
+ | || | ||
git push | git push | ||
− | + | ! [rejected] martins-test-1 -> martins-test-1 (fetch first) | |
error: failed to push some refs to 'https://gitlab.com/freepascal.org/lazarus_testconversion.git' | error: failed to push some refs to 'https://gitlab.com/freepascal.org/lazarus_testconversion.git' | ||
− | + | Instead of the normal pull, we do a fetch. This will not resolve the problem, but we can see what it looks like. | |
− | Instead of the normal pull, we do a fetch. This will not resolve the problem, | ||
git fetch | git fetch | ||
− | |||
+ | git log --oneline --graph --all -n 3 | ||
+ | * 46a817b6b3 (origin/martins-test-1) test other | ||
+ | | * 3b007fdc38 (HEAD -> martins-test-1) test changes | ||
+ | |/ | ||
+ | | * c739dd68a7 (origin/master, origin/HEAD) Revert "Test a change in forms" | ||
− | + | || | |
− | |||
− | |||
− | |||
− | |||
+ | |- | ||
+ | | colspan="2" style="padding-left: 50px; font-size:88%;" | | ||
+ | For the [[#Merge]] example stop here, and continue in the next section | ||
+ | |- | ||
+ | || | ||
You can see your commit still follows the same commit as before. | You can see your commit still follows the same commit as before. | ||
Line 80: | Line 100: | ||
The history on the server is fixed. We do not allow for it to be changed. So that commit will keep its parent. | The history on the server is fixed. We do not allow for it to be changed. So that commit will keep its parent. | ||
− | In order to get your commit to the server, your local commit must change it's parent to "test other" ( | + | In order to get your commit to the server, your local commit must change it's parent to "test other" (this is called "rebase") |
git pull --rebase | git pull --rebase | ||
Line 93: | Line 113: | ||
git push | git push | ||
− | == Merge == | + | || |
+ | |||
+ | |} | ||
+ | |||
+ | === Merge === | ||
{{Warning| This example is what we want to avoid. This creates a diverged history (sub-branches). The log is no longer linear. }} | {{Warning| This example is what we want to avoid. This creates a diverged history (sub-branches). The log is no longer linear. }} | ||
+ | {| border=1 class="" style="text-align: left; border-collapse: collapse; padding: 10px; margin-left:10px;" | ||
+ | ! style="min-width: 60%; padding: 15px" | '''In Folder1''' | ||
+ | ! style="min-width: 30%; padding: 15px" | '''In Folder2 (other person)''' | ||
+ | |||
+ | |- | ||
+ | | colspan="2" style="padding-left: 50px;" | | ||
Setup new branches [[#Each example setup]] | Setup new branches [[#Each example setup]] | ||
− | Repeat the steps above until you done "git fetch" | + | |
+ | Repeat the steps from [[#Rebase]] above until you have done "git fetch" and reached the note for the "merge example" | ||
+ | |||
+ | |- | ||
+ | || | ||
Now run | Now run | ||
Line 106: | Line 140: | ||
1 file changed, 3 deletions(-) | 1 file changed, 3 deletions(-) | ||
− | The --no-ff --no-rebase | + | The --no-ff --no-rebase overrides any configs you may have made, and gets you the default behaviour of merging. |
Git will open an editor for you, and ask for a commit message for the merge. The merge creates a new commit. | Git will open an editor for you, and ask for a commit message for the merge. The merge creates a new commit. | ||
git log --oneline --graph --all -n 4 | git log --oneline --graph --all -n 4 | ||
− | + | * 044d9288b7 (HEAD -> martins-test-2) Merge branch 'martins-test-2' of https://gitlab.com/freepascal.org/lazarus_testconversion into martins-test-2 | |
− | + | |\ | |
− | + | | * 379b633c88 (origin/martins-test-2) test other | |
− | + | * | cfa3def67c test changes | |
− | + | |/ | |
− | + | * 2cbe840e7e foo bar | |
As you can see the two commits are in different sub-branches (they are actually side by side). | As you can see the two commits are in different sub-branches (they are actually side by side). | ||
Line 124: | Line 158: | ||
But this creates a commit log, like you would never see in svn. | But this creates a commit log, like you would never see in svn. | ||
− | == Fast Forward == | + | || |
+ | |} | ||
+ | |||
+ | === Fast Forward === | ||
+ | {{Note| In this example you will not have made a commit. Only the other person will have made a commit}} | ||
+ | |||
+ | Fast-Forward (FF) can only happen if | ||
+ | * there are new commits from a someone else | ||
+ | * but you have not made a commit yourself | ||
+ | |||
+ | {| border=1 class="" style="text-align: left; border-collapse: collapse; padding: 10px; margin-left:10px;" | ||
+ | ! style="min-width: 60%; padding: 15px" | '''In Folder1''' | ||
+ | ! style="min-width: 30%; padding: 15px" | '''In Folder2 (other person)''' | ||
+ | |||
+ | |- | ||
+ | | colspan="2" style="padding-left: 50px;" | | ||
+ | Setup new branches [[#Each example setup]] | ||
+ | |||
+ | |- | ||
+ | || | ||
+ | Edit the file lcl/forms.pp | ||
+ | Do '''not''' commit the changes. | ||
+ | |||
+ | git status -uno | ||
+ | On branch martins-test-1 | ||
+ | Your branch is up to date with 'origin/martins-test-1'. | ||
+ | |||
+ | Changes not staged for commit: | ||
+ | (use "git add <file>..." to update what will be committed) | ||
+ | (use "git restore <file>..." to discard changes in working directory) | ||
+ | modified: lcl/forms.pp | ||
+ | |||
+ | Your changes are relative to the last commit | ||
+ | git log --oneline -n1 | ||
+ | c739dd68a7 (HEAD -> martins-test-1) Foo bar" | ||
+ | |||
+ | || | ||
+ | |||
+ | |- | ||
+ | || | ||
+ | || | ||
+ | Edit the file ide/main.pp | ||
+ | git commit -m 'test other' ide/main.pp | ||
+ | git push | ||
+ | |||
+ | |- | ||
+ | || | ||
+ | Fetch the data from the remote | ||
+ | git fetch | ||
+ | |||
+ | Status will tell you you are behind the remote | ||
+ | git status -uno | ||
+ | On branch martins-test-1 | ||
+ | Your branch is behind 'origin/martins-test-1' by 1 commit, and can be fast-forwarded. | ||
+ | (use "git pull" to update your local branch) | ||
+ | |||
+ | Changes not staged for commit: | ||
+ | (use "git add <file>..." to update what will be committed) | ||
+ | (use "git restore <file>..." to discard changes in working directory) | ||
+ | modified: lcl/forms.pp | ||
+ | |||
+ | Your changes are still relative to the last local commit. Indicated by "HEAD" | ||
+ | git log --oneline -n2 origin/martins-test-1 | ||
+ | bc20668e78 (origin/martins-test-1) test other | ||
+ | c739dd68a7 (HEAD -> martins-test-1) Foo bar" | ||
+ | |||
+ | git pull --ff-only | ||
+ | Updating c739dd68a7..bc20668e78 | ||
+ | Fast-forward | ||
+ | ide/main.pp | 2 ++ | ||
+ | 1 file changed, 2 insertions(+) | ||
+ | |||
+ | Now the local branch "martins-test-1" has caught up to the remote branch. It includes the new commits. And it switched to the top commit. | ||
+ | <br/>This catching up, is a fast forward. | ||
+ | * No local branches commits where changed/moved/added. Only the branch pointer moved | ||
+ | * Your changes are still there, and are now relative to the top commit | ||
+ | |||
+ | git log --oneline -n2 --graph origin/martins-test-1 | ||
+ | bc20668e78 (HEAD -> martins-test-1, origin/martins-test-1) test other | ||
+ | c739dd68a7 Foo bar" | ||
+ | |||
+ | || | ||
+ | |} | ||
+ | |||
+ | == Conflict Resolution == | ||
+ | |||
+ | === Getting selected upstream changes === | ||
+ | |||
+ | |||
+ | {| border=1 class="" style="text-align: left; border-collapse: collapse; padding: 10px; margin-left:10px;" | ||
+ | ! style="min-width: 60%; padding: 15px" | '''In Folder1''' | ||
+ | ! style="min-width: 30%; padding: 15px" | '''In Folder2 (other person)''' | ||
+ | |||
+ | |- | ||
+ | | colspan="2" style="padding-left: 50px;" | | ||
+ | Setup new branches [[#Each example setup]] | ||
+ | |||
+ | |- | ||
+ | || | ||
+ | Edit the file lcl/forms.pp<br/> | ||
+ | Edit the file ide/main.pp somewhere from line 100 down | ||
+ | |||
+ | git diff --stat | ||
+ | ide/main.pp | 5 +++++ | ||
+ | lcl/forms.pp | 4 ++++ | ||
+ | 2 files changed, 9 insertions(+) | ||
+ | |||
+ | git log --oneline -n 1 | ||
+ | c739dd68a7 (HEAD -> martins-test-1) Foo Bar" | ||
+ | |||
+ | || | ||
+ | |||
+ | |- | ||
+ | || | ||
+ | || | ||
+ | Edit the file ide/main.pp somewere in the first 20 lines (no conflict with the main user in folder1)<br/> | ||
+ | Also edit the file lcl/grids.pas | ||
+ | git commit -m 'test other' -a | ||
+ | git push | ||
+ | |||
+ | |- | ||
+ | || | ||
+ | Update from remote. Keep current commit as base for your changes | ||
+ | git fetch | ||
+ | git log --oneline -n2 origin/martins-test-1 | ||
+ | 810b4f1bd4 (origin/martins-test-1) test other | ||
+ | c739dd68a7 (HEAD -> martins-test-1) Foo Bar | ||
+ | |||
+ | The commit "test other" changes several files. For testing you want to integrate the changes in file ide/main.pp, but no other changes. | ||
+ | git stash | ||
+ | git restore --source=origin/martins-test-1 ide/main.pp | ||
+ | git commit -m 'dummy commit' ide/main.pp | ||
+ | git stash pop | ||
+ | |||
+ | Now you have a dummy commit with the changes to test. And your changes applied on top. | ||
+ | git log --oneline -n2 | ||
+ | 63e2dcec9f (HEAD -> martins-test-1) dummy commit | ||
+ | c739dd68a7 Foo Bar | ||
+ | git diff --stat | ||
+ | ide/main.pp | 5 +++++ | ||
+ | lcl/forms.pp | 4 ++++ | ||
+ | 2 files changed, 9 insertions(+) | ||
+ | |||
+ | Now work with those changes, make further changes, eventually commit | ||
+ | git commit -m 'my changes' -a | ||
+ | [martins-test-1 9aba7218d1] my changes | ||
+ | 2 files changed, 9 insertions(+) | ||
+ | |||
+ | git log --oneline -n5 --graph --all | ||
+ | * 9aba7218d1 (HEAD -> martins-test-1) my changes | ||
+ | * 63e2dcec9f dummy commit | ||
+ | | * 810b4f1bd4 (origin/martins-test-1) test other | ||
+ | |/ | ||
+ | * c739dd68a7 Foo Bar | ||
+ | |||
+ | So you now need to rebase your changes on the origin/martins-test-1 to commit them. | ||
+ | git pull --rebase | ||
+ | Successfully rebased and updated refs/heads/martins-test-1. | ||
+ | |||
+ | git log --oneline -n3 | ||
+ | f0d6afd90d (HEAD -> martins-test-1) my changes | ||
+ | 810b4f1bd4 (origin/martins-test-1) test other | ||
+ | c739dd68a7 Foo Bar | ||
+ | |||
+ | The "dummy commit" is gone. Because it was identical to existing changes. | ||
+ | Of course you should check this. If it is still there you need to drop it with | ||
+ | git rebase -i | ||
+ | |||
+ | || | ||
+ | |} | ||
+ | |||
− | + | [[Category:Version Control]] |
Latest revision as of 06:44, 29 December 2021
This page has some exercises so you can experience different solutions/outcomes for a given task.
By providing these (partly trivial) examples, the page ensures that you will not miss any of the scenarios while discovering the wonders of GIT.
Preface
Some of the examples are about how to deal with your work when other people are pushed in between.
For this you need a 2nd clone. See setup.
Setup
The following steps should be performed before going to any of the below items.
- Initial setup and clone
- Second clone
To simulate what someone else would have done while you where working. This can use the same user, the effect will be the same.
You can either "git clone" again, or just make a copy of the entire directory into which you have cloned.
You can then in that 2nd clone alter your username
git config user.name martin_2
Each example setup
In your first git folders, create a new branch
git switch -c martins-test-1 git push --set-upstream origin martins-test-1 ## tell the server there is a new branch
In your 2nd git folder
git remote update git switch martins-test-1
Thus both your folders are at the same branch, and are up to date with the remote
Pushing your commit, if someone else made changes
Note: If you followed the configuration your "git pull" should be configured to default to either "--ff-ony" or "--rebase".
The arguments given in to "pull" in the examples, will override the defaults
Rebase
In Folder1 | In Folder2 (other person) |
---|---|
Setup new branches #Each example setup | |
Edit the file lcl/forms.pp git commit -m 'test changes' lcl/forms.pp git log --oneline --graph --all -n 2 * 3b007fdc38 (HEAD -> martins-test-1) test changes * c739dd68a7 (origin/master, origin/HEAD) Revert "Test a change in forms" Your commit, follows the previous commit |
|
Edit the file ide/main.pp git commit -m 'test other' ide/main.pp git push | |
git push ! [rejected] martins-test-1 -> martins-test-1 (fetch first) error: failed to push some refs to 'https://gitlab.com/freepascal.org/lazarus_testconversion.git' Instead of the normal pull, we do a fetch. This will not resolve the problem, but we can see what it looks like. git fetch git log --oneline --graph --all -n 3 * 46a817b6b3 (origin/martins-test-1) test other | * 3b007fdc38 (HEAD -> martins-test-1) test changes |/ | * c739dd68a7 (origin/master, origin/HEAD) Revert "Test a change in forms" |
|
For the #Merge example stop here, and continue in the next section | |
You can see your commit still follows the same commit as before. But on the server (origin/martins-test-1) there is the other commit, and it too has the same parent. The history on the server is fixed. We do not allow for it to be changed. So that commit will keep its parent. In order to get your commit to the server, your local commit must change it's parent to "test other" (this is called "rebase") git pull --rebase Successfully rebased and updated refs/heads/martins-test-1. git log --oneline --graph --all -n 3 * 2cbe840e7e (HEAD -> martins-test-1) test changes * 46a817b6b3 (origin/martins-test-1) test changes * c739dd68a7 (origin/master, origin/HEAD) Revert "Test a change in forms" Now your commit is on top, and we have a flat line of commits (like svn) git push |
Merge
Warning: This example is what we want to avoid. This creates a diverged history (sub-branches). The log is no longer linear.
In Folder1 | In Folder2 (other person) |
---|---|
Setup new branches #Each example setup Repeat the steps from #Rebase above until you have done "git fetch" and reached the note for the "merge example" | |
Now run git pull --no-ff --no-rebase Merge made by the 'recursive' strategy. ide/main.pp | 3 --- 1 file changed, 3 deletions(-) The --no-ff --no-rebase overrides any configs you may have made, and gets you the default behaviour of merging. Git will open an editor for you, and ask for a commit message for the merge. The merge creates a new commit. git log --oneline --graph --all -n 4 * 044d9288b7 (HEAD -> martins-test-2) Merge branch 'martins-test-2' of https://gitlab.com/freepascal.org/lazarus_testconversion into martins-test-2 |\ | * 379b633c88 (origin/martins-test-2) test other * | cfa3def67c test changes |/ * 2cbe840e7e foo bar As you can see the two commits are in different sub-branches (they are actually side by side). And a new merge commit has been added. You can push this. But this creates a commit log, like you would never see in svn. |
Fast Forward
Fast-Forward (FF) can only happen if
- there are new commits from a someone else
- but you have not made a commit yourself
In Folder1 | In Folder2 (other person) |
---|---|
Setup new branches #Each example setup | |
Edit the file lcl/forms.pp Do not commit the changes. git status -uno On branch martins-test-1 Your branch is up to date with 'origin/martins-test-1'. Changes not staged for commit: (use "git add <file>..." to update what will be committed) (use "git restore <file>..." to discard changes in working directory) modified: lcl/forms.pp Your changes are relative to the last commit git log --oneline -n1 c739dd68a7 (HEAD -> martins-test-1) Foo bar" |
|
Edit the file ide/main.pp git commit -m 'test other' ide/main.pp git push | |
Fetch the data from the remote git fetch Status will tell you you are behind the remote git status -uno On branch martins-test-1 Your branch is behind 'origin/martins-test-1' by 1 commit, and can be fast-forwarded. (use "git pull" to update your local branch) Changes not staged for commit: (use "git add <file>..." to update what will be committed) (use "git restore <file>..." to discard changes in working directory) modified: lcl/forms.pp Your changes are still relative to the last local commit. Indicated by "HEAD" git log --oneline -n2 origin/martins-test-1 bc20668e78 (origin/martins-test-1) test other c739dd68a7 (HEAD -> martins-test-1) Foo bar" git pull --ff-only Updating c739dd68a7..bc20668e78 Fast-forward ide/main.pp | 2 ++ 1 file changed, 2 insertions(+) Now the local branch "martins-test-1" has caught up to the remote branch. It includes the new commits. And it switched to the top commit.
git log --oneline -n2 --graph origin/martins-test-1 bc20668e78 (HEAD -> martins-test-1, origin/martins-test-1) test other c739dd68a7 Foo bar" |
Conflict Resolution
Getting selected upstream changes
In Folder1 | In Folder2 (other person) |
---|---|
Setup new branches #Each example setup | |
Edit the file lcl/forms.pp git diff --stat ide/main.pp | 5 +++++ lcl/forms.pp | 4 ++++ 2 files changed, 9 insertions(+) git log --oneline -n 1 c739dd68a7 (HEAD -> martins-test-1) Foo Bar" |
|
Edit the file ide/main.pp somewere in the first 20 lines (no conflict with the main user in folder1) git commit -m 'test other' -a git push | |
Update from remote. Keep current commit as base for your changes git fetch git log --oneline -n2 origin/martins-test-1 810b4f1bd4 (origin/martins-test-1) test other c739dd68a7 (HEAD -> martins-test-1) Foo Bar The commit "test other" changes several files. For testing you want to integrate the changes in file ide/main.pp, but no other changes. git stash git restore --source=origin/martins-test-1 ide/main.pp git commit -m 'dummy commit' ide/main.pp git stash pop Now you have a dummy commit with the changes to test. And your changes applied on top. git log --oneline -n2 63e2dcec9f (HEAD -> martins-test-1) dummy commit c739dd68a7 Foo Bar git diff --stat ide/main.pp | 5 +++++ lcl/forms.pp | 4 ++++ 2 files changed, 9 insertions(+) Now work with those changes, make further changes, eventually commit git commit -m 'my changes' -a [martins-test-1 9aba7218d1] my changes 2 files changed, 9 insertions(+) git log --oneline -n5 --graph --all * 9aba7218d1 (HEAD -> martins-test-1) my changes * 63e2dcec9f dummy commit | * 810b4f1bd4 (origin/martins-test-1) test other |/ * c739dd68a7 Foo Bar So you now need to rebase your changes on the origin/martins-test-1 to commit them. git pull --rebase Successfully rebased and updated refs/heads/martins-test-1. git log --oneline -n3 f0d6afd90d (HEAD -> martins-test-1) my changes 810b4f1bd4 (origin/martins-test-1) test other c739dd68a7 Foo Bar The "dummy commit" is gone. Because it was identical to existing changes. Of course you should check this. If it is still there you need to drop it with git rebase -i |