Git and GitHub Interview Questions and Answers: 60 Questions from Easy to Hard

$ git log --oneline -2
9f9c576 Add f2
b49055e Add f1
$ git rebase main
Successfully rebased and updated refs/heads/feature.
$ git log --oneline --graph
* a24768c Add f2
* 61d082b Add f1
* bd3db9f Main work
* 74dd0b2 base
$ git switch main
$ git merge feature
Updating bd3db9f..a24768c
Fast-forward

$ git commit --fixup=HEAD~1
[feature a0f30b5] fixup! Add pay endpoint
$ git log --oneline main..
a0f30b5 fixup! Add pay endpoint
0933db9 Add tests
9285e63 Add pay endpoint
$ git rebase -i --autosquash main     # todo list saved as shown
Successfully rebased and updated refs/heads/feature.
$ git log --oneline main..
593ad06 Add tests
d9ded00 Add pay endpoint

$ git reset --soft HEAD~1
$ git status --short
A  b
# commit again, then
$ git reset HEAD~1          # same as --mixed
$ git status --short
?? b
# add and commit again, then
$ git reset --hard HEAD~1
HEAD is now at d582fb2 one
$ git status --short
$ ls
a

$ git revert HEAD
error: commit 894ccc4ac25864962385b6f62762a151fa0ad7a2 is a merge but no -m option was given.
fatal: revert failed
$ git revert -m 1 --no-edit HEAD
[main 87f9bff] Revert "Merge branch 'feature'"
$ ls -C
a  m

$ git reset --hard HEAD~2
HEAD is now at 359b42d Add f
$ git reflog
359b42d HEAD@{0}: reset: moving to HEAD~2
2d2059e HEAD@{1}: commit: Add invoice PDF
672a5dd HEAD@{2}: commit: Add GST calculation
359b42d HEAD@{3}: commit (initial): Add f
$ git reset --hard HEAD@{1}
HEAD is now at 2d2059e Add invoice PDF

$ git switch release/2.4
$ git cherry-pick -x main~1
[release/2.4 cd0511f] Fix rounding in GST total
$ git log -1 --format=%B
Fix rounding in GST total

(cherry picked from commit d3e52b9242bbe88f6f5f9c5f8c256eb3b6ece5c4)

$ git rebase main
CONFLICT (content): Merge conflict in tax.cfg
error: could not apply 0f9d1eb... Feature rate
$ git checkout --ours tax.cfg
$ cat tax.cfg
rate=5
$ git checkout --theirs tax.cfg
$ cat tax.cfg
rate=12
$ git add tax.cfg
$ git rebase --continue

$ git stash pop
Auto-merging app.py
CONFLICT (content): Merge conflict in app.py
...
The stash entry is kept in case you need it again.
$ git stash list
stash@{0}: WIP on main: 733758d one
# resolve app.py and git add it, then
$ git stash drop

# .idea/ written to ~/.config/git/ignore and
# scratch.txt added to .git/info/exclude, then
$ git check-ignore -v .idea/ws.xml scratch.txt debug.log
.../.config/git/ignore:1:.idea/	.idea/ws.xml
.git/info/exclude:7:scratch.txt	scratch.txt
.gitignore:1:*.log	debug.log

$ git pull
...
hint: You have divergent branches and need to specify how to reconcile them.
...
fatal: Need to specify how to reconcile divergent branches.
$ git pull --ff-only
fatal: Not possible to fast-forward, aborting.
$ git pull --rebase
Successfully rebased and updated refs/heads/main.
$ git log --oneline --graph
* 2465776 Priya work
* bf8297b Rahul work
* 74dd0b2 base

$ git push
...
 ! [rejected]        main -> main (fetch first)
...
hint: Updates were rejected because the remote contains work that you do not
hint: have locally. This is usually caused by another repository pushing to
...
$ git pull --rebase
$ git push
...
   bf8297b..2465776  main -> main

# Rahul pushed a commit to feature after you amended yours
$ git push --force-with-lease
 ! [rejected]        feature -> feature (stale info)
$ git fetch
...
feature    -> origin/feature
$ git push --force-with-lease --force-if-includes
 ! [rejected]        feature -> feature (remote ref updated since checkout)
$ git push --force-with-lease
 + 9811ff9...0d49ecb feature -> feature (forced update)
# Rahul's commit is now gone from the remote

$ git rev-parse --short HEAD
93d5f62
$ git add test.py
$ git commit --amend --no-edit
[main b751664] Add login
$ git rev-parse --short HEAD
b751664
# after pushing, amending again and pushing
$ git push
...
 ! [rejected]        main -> main (non-fast-forward)

$ git push origin main
...
 * [new branch]      main -> main
$ git ls-remote --tags origin
# (no output: no tags on the remote yet)
$ git push origin v1.1.0
...
 * [new tag]         v1.1.0 -> v1.1.0
# new commit, annotated tag v1.2.0, then
$ git push --follow-tags
...
 * [new tag]         v1.2.0 -> v1.2.0

$ cat ../check.sh
#!/bin/sh
grep -q 1.18 calc.txt
$ git bisect start HEAD HEAD~7
$ git bisect run ../check.sh
...
is the first bad commit
...
    Change 6
$ git bisect reset
...
Switched to branch 'main'

$ git log --oneline main..feature/login
1eef6e3 two
$ git switch main
$ git branch -d feature/login
error: the branch 'feature/login' is not fully merged.
If you are sure you want to delete it, run 'git branch -D feature/login'
$ git branch -D feature/login
Deleted branch feature/login (was 1eef6e3).

$ git remote add upstream https://github.com/ORIGINAL-OWNER/REPO.git
$ git remote -v
origin	...fork.git (fetch)
origin	...fork.git (push)
upstream	https://github.com/ORIGINAL-OWNER/REPO.git (fetch)
upstream	https://github.com/ORIGINAL-OWNER/REPO.git (push)
$ git fetch upstream
...
 * [new branch]      main       -> upstream/main
$ git switch main
$ git merge --ff-only upstream/main
Fast-forward
$ git push origin main

name: CI
on:
  pull_request:
    branches: [main]
  push:
    branches: [main]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: 20
      - run: npm ci
      - run: npm test