Write a C Program Without a main() Function
by Başar Subaşı
Produce a valid ELF binary that runs and exits cleanly, but does not define a main() function.
Challenges
Focused, hands-on problems for sharpening your DevOps and server-side skills. Some teach specific concepts while others mirror real-world scenarios. Every challenge includes hints, feedback, and automated solution checks.
Make One Echo Server Work with Both TCP and Unix Sockets
Make a single echo server listen on either a TCP socket or a Unix domain socket, selected by its command-line argument. The challenge illustrates that the same stream-socket workflow works with two address families (AF_INET and AF_UNIX).
Submissions: 47/86
Write a TCP Client for a Chat Server
Write a TCP client to hold a back-and-forth conversation with a "chat" server: send a line, read the reply, send another line - repeat until the session is over. A hands-on lesson in designing an application protocol on top of a byte-oriented TCP stream.
Write a TCP Echo Server From Scratch
The Hello World of network programming: implement a tiny TCP echo server in the language of your choice.
Optimize Container Images with Multi-Stage Builds
Practice optimizing applications' container images using multi-stage builds. Rewrite single-stage Dockerfiles for a Go backend and a TypeScript frontend to produce smaller, production-ready images without unnecessary build tools and dev dependencies.
Submissions: 137/226
Build and Compile Applications in Dockerfiles
Practice building and compiling applications inside their Dockerfiles by containerizing a Go backend and a TypeScript frontend.
Submissions: 154/246
Build a Production-Ready Go Container Image: A Statically Linked Application
Learn how to build a secure, lightweight, and production-ready container image for a statically linked Go application by following this hands-on challenge full of practical tips and tricks.
Submissions: 164/317
Build a Production-Ready Node.js Container Image: SvelteKit Application
Learn how to build a secure, lightweight, and production-ready Node.js container image for a SvelteKit application by following this hands-on challenge full of practical tips and tricks.
Submissions: 90/149
Build a Production-Ready Node.js Container Image: Next.js Application
Learn how to build a secure, lightweight, and production-ready Node.js container image for a Next.js application by following this hands-on challenge full of practical tips and tricks.
Submissions: 168/447
Build a Production-Ready Node.js Container Image: Nuxt Application
Learn how to build a secure, lightweight, and production-ready Node.js container image for a Nuxt application by following this hands-on challenge full of practical tips and tricks.
Submissions: 100/148