HTTP methods are the verbs of a REST API. The URI identifies the resource; the method identifies what to do with it. This separation is the core of the uniform interface constraint: the same URI can support multiple operations, and the operation is expressed by the method rather than by a verb in the path…
A REST API’s URI structure is not cosmetic. It is the contract that clients navigate, the surface that documentation describes, and the layer where the difference between a well-designed API and an inconsistent one becomes visible. The uniform interface constraint from the previous chapter requires that every resource be identified by a URI, but it…
REST is not a protocol, a library, or a standard. It is an architectural style—a set of design constraints that, when applied together, produce a system with specific desirable properties: scalability, loose coupling, independent deployability, and the ability to evolve without breaking clients . Roy Fielding defined it in his 2000 doctoral dissertation as an…
DNF (Dandified YUM) is the package manager for RHEL, Fedora, Rocky Linux, AlmaLinux, and other RPM-based distributions. It replaced YUM as the default in Fedora 22 and became the standard in RHEL 8 and later . The relationship between the two commands is simpler than it appears: on RHEL 8 and 9, yum is an…
APT (Advanced Package Tool) is the package management system used by Debian, Ubuntu, and their derivatives. It sits on top of dpkg, the low-level tool that installs and removes individual .deb files, and adds the repository logic, dependency resolution, and network retrieval that make installing software practical . For the LFCS exam, package management falls…
Shell history is the mechanism that records every command you type, lets you recall and re-execute them, and persists them across sessions in a file. For the LFCS exam, this falls under the “Essential Commands” domain and the “User and Group Management” domain, specifically “Manage template user environment” and “Use shell/environment variables” . The history…
A shell function is a named block of commands that the shell executes in the current process, as if you had typed each line yourself. Unlike a script, which runs in a new process with its own environment, a function shares the shell’s variables, its working directory, and its file descriptors . This is the…
A shell alias is a name that the shell substitutes for a command before executing it. When you type ll, the shell replaces it with ls -alF and runs the result. The mechanism is simple, but the rules around it are not: aliases are expanded only when the shell reads a line, only for interactive…
A Vue Router configuration has two persistent weaknesses as an application grows. The first is that route names and parameters are strings. A typo in router.push({ name: ‘user-profile’ }) when the route is actually named ‘userProfile’ compiles without error and fails at runtime. The second is that data fetching lives inside the component’s onMounted hook,…
A Vue Router configuration is not just a list of paths and components. It is a place to attach arbitrary data to each route—whether a page requires authentication, what transition animation it should use, or what title to set on the document. That data lives in the meta field, and it is accessible from the…