A script that fails silently or behaves unexpectedly is a script that needs debugging. The shell provides three mechanisms for this: set -x prints each command before executing it, set -v prints each line before parsing it, and the -n flag parses the script without executing it. Beyond these, there are the PS4 prompt customization,…
The previous chapters covered the syntax of scripts: variables, conditionals, loops, functions, and arguments. This chapter covers the behavior of a script when something goes wrong. A script without error handling fails silently. A command fails, the script continues, and the failure is masked by a later successful command. The exit code is 0, the…
The previous chapters covered positional parameters, special variables, and conditionals. This chapter focuses on the practical problem of argument parsing: how a script accepts options like -v, –verbose, or -f file, validates them, and behaves accordingly. The LFCS exam tests the getopts builtin, the manual while/case/shift pattern, and the difference between short options (-v) and…
The previous chapter covered deploying applications to named environments. This chapter covers the mechanism that connects GitLab to a Kubernetes cluster and the workflow that keeps the cluster synchronized with a Git repository. GitLab provides a Kubernetes agent that runs inside the cluster and maintains a bidirectional connection to GitLab. The recommended workflow is GitOps:…
A pipeline that builds and tests without deploying is a pipeline that stops at the last mile. GitLab provides a structured deployment mechanism through environments: named targets (staging, production, review apps) with their own variables, deployment history, and protection rules. The exam tests the environment keyword, the distinction between a review app and a staging…
A pipeline that builds and tests without scanning for vulnerabilities is a pipeline that ships risk. GitLab provides three core security scanners as CI/CD templates: Static Application Security Testing (SAST) analyzes source code for injection flaws and insecure patterns, Secret Detection scans for accidentally committed credentials, and Dependency Scanning checks third-party libraries against known vulnerability…
A pipeline that builds and deploys without testing is a pipeline that ships bugs. GitLab provides three distinct mechanisms for quality assurance: the test job itself (which runs the suite and fails the pipeline on failure), the code quality report (which surfaces static analysis findings in the merge request), and the coverage report (which displays…
The GitLab Container Registry is the built-in registry for storing Docker images and OCI artifacts alongside the source code. It is not an external service like Docker Hub; it is a component of the GitLab instance, accessible at registry.gitlab.com on GitLab.com or at a configured hostname on self-managed instances. The exam tests the CI/CD integration:…
A function is a named block of commands that can be called multiple times within a script. It is the mechanism for eliminating repetition and for encapsulating logic that would otherwise be duplicated. The LFCS exam tests the syntax of the function definition, the scope of variables within a function, the mechanism for returning values,…
The previous chapter covered conditionals: the if statement, the test command, and the case statement. This chapter covers loops: for, while, and until. These are the constructs that repeat a block of commands. The LFCS exam tests the syntax of the for loop over a list and over a range, the while loop with a…