Developer guides
Developer How-To Guides
Practical, copy-ready answers to the commands developers look up most: undoing Git commits, deleting branches, cleaning up Docker, freeing a busy port, generating SSH keys, scheduling cron jobs, finding files on Linux and setting up Python virtual environments. Each guide explains when to use each option and which ones can lose data, with Windows, macOS and Linux variants where they differ.
Git
Undo commits, clean up branches and choose between rebase and merge.
- How to Undo the Last Commit in GitHow to undo the last Git commit: git reset --soft, --mixed or --hard, git revert for pushed commits, git commit --amend, and recovering work with reflog.Read guide
- How to Delete a Git Branch (Local and Remote)Delete a Git branch locally (git branch -d vs -D) and remotely (git push origin --delete), prune stale branches, bulk-delete merged ones and recover mistakes.Read guide
- Git Rebase vs Merge: What's the Difference and When to Use EachGit rebase vs merge with history diagrams: how each works, when to rebase, the golden rule, interactive rebase, pull --rebase, squash merges and conflicts.Read guide
Docker
Clean up containers, images and volumes safely.
Linux & Shell
Ports, processes, SSH keys, finding files and scheduling jobs.
- How to Kill a Process Running on a PortFind and kill the process using a port (3000, 8080) on macOS, Linux and Windows with lsof, ss, fuser, netstat + taskkill, PowerShell and npx kill-port.Read guide
- How to Generate an SSH Key (Windows, macOS and Linux)Generate an SSH key with ssh-keygen (Ed25519 or RSA 4096) on Windows, macOS and Linux, add it to GitHub, load it into ssh-agent and copy it to a server.Read guide
- How to Find a File in Linux (find Command Guide)Find files in Linux by name (-name, -iname), type, size and modified time with the find command, use -exec and -delete safely, and try locate, fd and grep -r.Read guide
- How to Run a Cron Job Every 5 MinutesRun a cron job every 5 minutes with */5 * * * *: examples for every minute, hour, day and weekday, PATH pitfalls, logging, systemd timers and GitHub Actions.Read guide
Python
Isolated environments and dependency management.
Computer science
Fundamentals for interviews and everyday problem solving.