Developer & Tech Command Cheat Sheets
Quickly search and copy high-utility commands for Linux server administration, Git version control, Docker container operations, and SQL database pipelines.
Chmod 755 (Read/Execute for all, Write for Owner)
Sets rwxr-xr-x permissions. Standard for executable web scripts and directories.
chmod 755 filename.sh
Find Files Larger Than 100MB
Searches root partition for giant files eating up storage.
find / -type f -size +100M -exec ls -lh {} \;Create Gzip Compressed Tarball
-c (create), -z (gzip), -v (verbose), -f (filename). Archives directory.
tar -czvf backup-archive.tar.gz /var/www/html
Kill Process Running on Specific Port
Instantly frees locked port 3000 or 8080.
fuser -k 3000/tcp || npx kill-port 3000
Inspect Live Server Resource Usage
Interactive real-time process monitoring sorted by CPU usage.
htop || top -o %CPU
Interactive Rebase Last N Commits
Squash, edit, or reorder the last 3 local commits before pushing to remote.
git rebase -i HEAD~3
Undo Last Commit but Keep Staged Changes
Moves HEAD back 1 commit without touching your modified files in working directory.
git reset --soft HEAD~1
Stash Changes with Custom Descriptive Message
Shelves dirty working tree state with a searchable tag.
git stash push -m 'WIP: auth integration refactor'
Cherry-Pick Specific Commit to Current Branch
Applies the exact diff of a commit from another branch to current HEAD.
git cherry-pick a1b2c3d4
Force Delete Local and Remote Branch
Prunes abandoned or merged feature branch everywhere.
git branch -D feature/login && git push origin --delete feature/login
Run Background Container with Port Forwarding
Runs nginx container detached in background mapped to host port 8080.
docker run -d -p 8080:80 --name my-web-app nginx:alpine
Clean All Unused Containers, Networks & Images
Reclaims tens of gigabytes of disk space by pruning dangling cache and unused layers.
docker system prune -a --volumes -f
Tail Container Live Output Logs
Streams recent 100 stdout lines in real-time.
docker logs -f --tail 100 <container-id>
Execute Interactive Bash Shell Inside Container
Opens terminal prompt inside running Alpine or Debian container.
docker exec -it <container-id> /bin/sh
200 OK vs 201 Created
Use 201 when a POST or PUT creates a new persistent resource.
HTTP/1.1 201 Created Location: /api/v1/orders/108
301 Moved Permanently vs 302 Found
301 passes 99% SEO link equity (PageRank). 302 is temporary and doesn't update indexing.
HTTP/1.1 301 Moved Permanently Location: https://example.com/new-url
401 Unauthorized vs 403 Forbidden
401 is authentication (identity unknown). 403 is authorization (identity known, but no access).
HTTP/1.1 401 Unauthorized (Missing/Expired JWT) HTTP/1.1 403 Forbidden (Valid JWT, but not Admin)
502 Bad Gateway vs 504 Gateway Timeout
Critical difference when debugging microservices behind Cloudflare or AWS ALB.
502: Reverse proxy (Nginx) got invalid response from upstream (Node/Python). 504: Upstream did not respond before proxy timeout.
Rank Items by Revenue (Window Function)
Calculates intra-department salary rank without collapsing rows with GROUP BY.
SELECT employee_id, department, salary, DENSE_RANK() OVER (PARTITION BY department ORDER BY salary DESC) as rank FROM employees;
Find Duplicate Emails in Users Table
Filters aggregate groups using HAVING to detect duplicate account records.
SELECT email, COUNT(*) FROM users GROUP BY email HAVING COUNT(*) > 1;
Common Table Expression (CTE) For Clean Pipelines
Readable modular subqueries replacing messy nested joins.
WITH active_subs AS ( SELECT user_id, plan_id, created_at FROM subscriptions WHERE status = 'active' ) SELECT u.email, s.plan_id FROM users u JOIN active_subs s ON u.id = s.user_id;