▸case-01 I accidentally ran a git rebase that went wrong and deleted my commit history on the feature branch. My colleague suggested running `git reset --hard HEAD~10` to guess where I was, but I need to recover the exact lost commits before the rebase without guessing commit hashes. What git command finds all previous HEAD positions? | pass→pass | 8,823 | 3,893 | -56% | 1 | 1 | 0% | 1,527 | 654 | -57% | 0 | 0 | — |
▸case-02 When running `git status` in my repository, I receive `error: bad index file` and `fatal: index file corrupt`. A common quick fix people try is running `git clean -fdx`, but that will delete my untracked source files. What is the standard safe fix to repair a corrupted Git index file without losing working directory changes? | pass→pass | 7,459 | 5,768 | -23% | 1 | 1 | 0% | 1,342 | 1,005 | -25% | 0 | 0 | — |
▸case-03 In Python 3.11, installing packages with pip fails due to conflicting dependency sub-versions across transitive packages. A naive workaround is using `--no-deps` or `--force-reinstall`, which breaks runtime imports. What official pip command option checks for dependency resolution conflicts across installed packages in the active environment? | pass→pass | 7,079 | 3,944 | -44% | 1 | 1 | 0% | 1,354 | 752 | -44% | 0 | 0 | — |
▸case-04 My Dockerfile builds an image using stale cached layers even though external remote assets fetched via `curl` inside the `RUN` step changed. The standard intuition is to delete the Docker image using `docker rmi`, but the build cache persists. What flag should be passed to `docker build` to ignore all cached layers and force every step to re-run? | pass→pass | 3,474 | 3,767 | +8% | 1 | 1 | 0% | 637 | 709 | +11% | 0 | 0 | — |
▸case-05 When making HTTPS requests to a private internal API using `curl`, I get `curl: (60) SSL certificate problem: unable to get local issuer certificate`. Colleagues keep recommending adding `-k` or `--insecure` to bypass validation entirely in production. What curl option explicitly specifies the path to a custom CA certificate bundle file to properly validate the connection? | pass→pass | 5,145 | 3,229 | -37% | 1 | 1 | 0% | 1,009 | 610 | -40% | 0 | 0 | — |
▸case-06 A systemd background service crashes immediately on startup and enters a rapid restart loop, generating thousands of log entries per minute. A developer suggested disabling the service via `systemctl disable`, but we need the service running while preventing infinite rapid restart storms. Which directive in the systemd service file's `[Service]` section sets a minimum delay between automatic restart attempts? | pass→pass | 5,117 | 5,235 | +2% | 1 | 1 | 0% | 804 | 763 | -5% | 0 | 0 | — |
▸case-07 A web service fails to parse a configuration file formatted in standard JSON because an automated script inserted a trailing comma after the last key-value pair. The developer wants to use `json.loads()` in Python with a special parameter to ignore syntax errors, but standard Python `json` does not support trailing commas. Which standard built-in command-line tool in Python validates JSON syntax and pinpoints the error? | pass→pass | 3,012 | 3,385 | +12% | 1 | 1 | 0% | 543 | 542 | -0% | 0 | 0 | — |
▸case-08 After re-imaging an Ubuntu build server, connecting via SSH fails with `REMOTE HOST IDENTIFICATION HAS CHANGED!`. Users often edit `~/.ssh/known_hosts` manually with text editors, which is prone to line number miscounts. Which OpenSSH utility command cleanly removes a specific host's outdated key from `~/.ssh/known_hosts`? | pass→pass | 2,765 | 2,590 | -6% | 1 | 1 | 0% | 563 | 515 | -9% | 0 | 0 | — |
▸case-09 A deployment directory contains hundreds of symlinks, several of which point to missing file paths (broken symlinks). A quick script using `ls -l | grep red` was proposed, but it fails in non-color terminals. Which flag option of the standard Linux `find` command specifically targets broken symbolic links directly? | pass→pass | 8,753 | 6,823 | -22% | 1 | 1 | 0% | 1,570 | 1,293 | -18% | 0 | 0 | — |
▸case-10 Running `npm install` in CI results in unexpected package updates that break tests because `package-lock.json` is out of sync with `package.json`. Developers usually delete `node_modules` and `package-lock.json` and re-run `npm install`, but that modifies the lockfile in CI. What npm command enforces installing exact dependencies from `package-lock.json` without modifying it, failing if out of sync? | pass→pass | 3,819 | 3,122 | -18% | 1 | 1 | 0% | 719 | 651 | -9% | 0 | 0 | — |
▸case-11 A long-running database query is holding an exclusive table lock, causing all subsequent queries to hang indefinitely. An engineer suggested restarting the PostgreSQL server daemon, but that causes unnecessary downtime for active connections. Which PostgreSQL system function safely terminates a specific backend process by its process ID (PID)? | pass→pass | 4,924 | 4,547 | -8% | 1 | 1 | 0% | 835 | 841 | +1% | 0 | 0 | — |
▸case-12 A Kubernetes pod fails immediately after startup and enters `CrashLoopBackOff`. Running `kubectl logs pod-name` returns empty output because the container already exited and restarted. What flag should be added to `kubectl logs` to view the logs from the previous failed container instance? | pass→pass | 2,076 | 2,228 | +7% | 1 | 1 | 0% | 412 | 403 | -2% | 0 | 0 | — |
▸case-13 An operator modified `/etc/nginx/nginx.conf` and wants to apply the changes, but running `systemctl reload nginx` directly risks taking down the web server if there is a syntax error. What Nginx command option tests the configuration files for syntax errors without restarting or reloading the service? | pass→pass | 3,603 | 2,628 | -27% | 1 | 1 | 0% | 558 | 418 | -25% | 0 | 0 | — |
▸case-14 A git tag verification command fails with `error: gpg.ssh.allowedSignersFile unset` when attempting to verify SSH-signed git tags. Developers usually try switching back to GPG keys or disabling signature verification with `--no-verify`. What Git configuration key sets the path to the allowed signers file required for SSH signature verification? | pass→pass | 2,803 | 2,862 | +2% | 1 | 1 | 0% | 569 | 546 | -4% | 0 | 0 | — |
▸case-15 Including header file `utils.h` in multiple source files causes C++ compilation to fail with `error: redefinition of 'struct UserData'`. Beginners often try adding `#undef` directives inside `.cpp` files, but this doesn't fix multiple inclusions. What standard preprocessor directive at the top of a header file prevents multiple inclusions? | pass→pass | 6,064 | 4,982 | -18% | 1 | 1 | 0% | 965 | 921 | -5% | 0 | 0 | — |
▸case-16 A Nginx reverse proxy returns `504 Gateway Time-out` when an upstream backend API takes longer than 60 seconds to process a heavy report. Developers try increasing `client_max_body_size`, but the connection still times out. Which Nginx directive increases the maximum allowed waiting time for reading a response from the upstream proxied server? | pass→pass | 5,053 | 3,825 | -24% | 1 | 1 | 0% | 788 | 749 | -5% | 0 | 0 | — |
▸case-17 Executing a bash script on Linux uploaded from Windows fails with `bash: ./deploy.sh: /bin/bash^M: bad interpreter: No such file or directory`. A user suggested opening the file in `nano` and re-saving, which leaves hidden control characters intact. Which utility program converts DOS/Windows CRLF line endings to Linux LF format? | pass→pass | 3,571 | 2,732 | -23% | 1 | 1 | 0% | 715 | 552 | -23% | 0 | 0 | — |
▸case-18 Running `df -h` shows `/var` is 100% full, but running `du -sh /var/*` shows only 10 GB used out of 100 GB. An admin attempted to reboot the server, but production requirements prevent downtime. Which Linux command lists deleted files that are still held open by running processes? | pass→pass | 5,334 | 3,784 | -29% | 1 | 1 | 0% | 973 | 673 | -31% | 0 | 0 | — |
▸case-19 A Rust program fails to compile with `error[E0502]: cannot borrow 'x' as immutable because it is also borrowed as mutable`. A developer tries inserting `unsafe` blocks around the references, which does not bypass borrow checker rules. How should the code structure be modified to resolve the conflicting borrows without unsafe code? | fail→pass | 15,067 | 13,042 | -13% | 1 | 1 | 0% | 2,737 | 2,093 | -24% | 0 | 0 | — |
▸case-20 I am committing a normal feature update to my git repository and want to follow best practices for writing a git commit message body and subject line. How should a standard commit subject line be formatted? | pass→pass | 10,165 | 9,948 | -2% | 1 | 1 | 0% | 1,789 | 1,482 | -17% | 0 | 0 | — |
▸case-21 I am building a brand new Node.js application using Express and need to create a simple HTTP GET route at `/api/status` that returns `{"status": "ok"}` with a 200 HTTP code. What code snippet sets up this route? | pass→pass | 4,783 | 2,847 | -40% | 1 | 1 | 0% | 834 | 537 | -36% | 0 | 0 | — |
▸case-22 I am starting a new Python 3.11 web application project from scratch and need to choose an official Docker base image that provides a minimal Debian-based footprint. What official Docker Hub Python tag is recommended for small Debian-based images? | pass→pass | 9,801 | 5,923 | -40% | 1 | 1 | 0% | 1,605 | 917 | -43% | 0 | 0 | — |