Selected Questions from LinkedIn Git Assessment

I took the LinkedIn Git assessment and got a certificate¹, but found that I am not super clear on some of the questions. Here is an analysis of some of the questions and their answers.

different ways of git add and their meaning

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I have written about this in this post.

git reset: soft vs mixed vs hard

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When using git-reset, there three different types of reset, in term of disruptiveness:

• --soft: moves HEAD to specified commit, and changes in the reset commits are squashed and kept in the staging area.
• --mixed: moves HEAD to specified commit, changes in the reset commits as well as changes in staging areas are moved to working tree. This is the default reset behaviour.
• --hard: moves HEAD to the specified commit, but all the changes (changes in the reset commit, in staging area , as well as changes in working tree) are discarded.

Ref:

• soft vs mixed vs hard: https://stackoverflow.com/a/50022436/6064933
• what does git reset do: https://stackoverflow.com/q/2530060/6064933

What the following command do:

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git checkout master
git cherry-pick kj2342134

It pick the commit kj2342134 and apply it on master, i.e., it will try to patch master branch with commit kj2342134.

Note we are likely to meet merge conflict. We need to resolve the conflict and then git add conflict_file, then run git cherry-pick --continue.

Ref:

• what does cherry-pick do? https://stackoverflow.com/q/9339429/6064933

show changes in files via git diff-tree

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git diff-tree --no-commit-id --name-status -r <SHA>

The output may look like this:

D       autocommands.vim
A       core/autocommands.vim
A       core/mappings.vim
A       core/options.vim
A       core/plugins.vim
A       core/ui.vim
A       core/variables.vim
M       init.vim
D       mappings.vim
D       options.vim
D       plugins.vim
D       ui.vim
D       variables.vim

Ref

https://stackoverflow.com/a/24819616/6064933

what does git commit -a do?

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It will stage modified and deleted files (but not new files) to staging area and commit them to index. So it is equivalent to the following two commands:

git add -u
git commit

Ref:

• https://stackoverflow.com/a/6840337/6064933

Status after modifying staged files

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Why do you see the following git status output?

On branch master
Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
        modified:   test.txt

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:   test.txt

It means that after test.txt is added to staging area, and you have changed it.

what does the following command do:

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git fetch --all
git reset --hard origin/master

It will fetch the remote changes, then discard all local changes and move HEAD to remote master. This will effectively make your local master the same as your remote master.

Ref:

• Difference between git pull and git fetch: https://stackoverflow.com/q/292357/6064933

Does git push push all tags to remote by default?

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No, if you create a tag locally, they are not pushed to remote by default when you do git push. To push a certain tag to remote, use:

git push origin {some-tag}

To push all tags to remote:

git push origin --tags

Ref:

• https://jdhao.github.io/2021/05/08/git_tag_notes/#push-tags-to-remote

check the help for a git subcommand

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For example, we want to check doc for git reset, how do we do it on command line? There are two ways:

• git help reset
• man git-reset

How do we restore to original state if we meet a merge conflict and decided to discard the changes?

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Use git merge --abort .

Ref:

• abort a merge: https://stackoverflow.com/a/2534968/6064933

Show branches that has been merged by current branch?

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Use git branch --merged

Clean untracked file in a repo?

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We can use git clean -f (-f means with force) to clean untracked files in a git repo.

Note that this will not remove untracked directories by default. To also remove untracked directories (be careful if you really want to), add -d option: git clean -d -f.

To see the dry-run result (do not actually delete the files), use --dry-run or -n.

difference between git fetch and git pull

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You can think of git-pull as a two step operation: first we use git fetch, then we use git merge to merge the remote tracking branch.

Show what is in a git stash without applying it

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First, use git stash list to list a list of stashes. The output is like this:

stash@{0}: WIP on feat: c6c7af1 4 and 5
stash@{1}: WIP on feat: c6c7af1 4 and 5
stash@{2}: WIP on feat: c6c7af1 4 and 5

Then, to see the changes in first stash, use git stash show -p stash@{0}. We can think of stash as a stack, where top is your most recent stashed changes.