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go install — Interview Q&A

Labeled by level. Concise answers.

Junior

Q1. What does go install do? It compiles a main package and copies the executable into your bin directory (GOBIN or $GOPATH/bin) so you can run it by name from anywhere.

Q2. How is it different from go build? go build writes the binary to the current directory (or -o path). go install writes it to the bin directory and names it after the package, making it runnable as a command.

Q3. You installed a tool but the shell says "command not found." Why? Your bin directory is not on PATH. Add $(go env GOPATH)/bin (or $(go env GOBIN)) to PATH.

Q4. How do you install a third-party CLI tool? go install path@version, e.g., go install honnef.co/go/tools/cmd/staticcheck@v0.5.1. The @version suffix is required for remote installs.

Middle

Q5. Where does the installed binary go, and what is it named? To GOBIN if set, otherwise $GOPATH/bin. The name is the last element of the package path (.../cmd/server → server). There is no -o.

Q6. What does @latest resolve to, and when should you avoid it? The highest released version (excluding pre-releases unless none exist). Avoid it in CI/scripts because it is non-reproducible; pin @vX.Y.Z there.

Q7. Does go install tool@version use your project's go.mod? No. With a version suffix it runs in isolated module mode, building the tool with its own dependencies and ignoring your go.mod.

Q8. How do you check which version of a tool is installed? go version -m "$(go env GOPATH)/bin/<tool>" prints the module path, version, and build settings baked into the binary.

Senior

Q9. Where do cross-compiled installs go? If GOOS/GOARCH differ from the host, into $GOPATH/bin/<goos>_<goarch>/ to avoid clobbering the native binary — unless GOBIN is set, which overrides that.

Q10. Why might go install tool@latest perform a network call even when nothing changed? @latest re-resolves the version on every invocation (a proxy/VCS query). The build may still be cached if the resolved version is unchanged, but the version query always happens.

Q11. How is go install a supply-chain concern? It downloads and runs third-party build logic with your privileges. Mitigate with pinned versions, a controlled GOPROXY, GOSUMDB/go.sum verification, and auditing installed binaries with go version -m.

Q12. Why might a global GOFLAGS=-mod=vendor break go install tool@version? The @version install needs module mode to resolve the tool's own graph, which conflicts with vendor mode. You may need -mod=mod or to unset GOFLAGS for the install.

Professional

Q13. How does a team eliminate tool version drift? Manage versions centrally: go.mod tool directives (Go 1.24+), a tools.go file, or pinned versions in a Makefile. Ban ad-hoc @latest in committed files and enforce it in review.

Q14. What's the modern way to track tools in a module? The Go 1.24 tool directive: go get -tool path adds a tool line to go.mod; then go install tool installs all pinned tools and go tool name runs one. Versions are reviewed alongside code.

Common traps

  • "command not found" → bin directory not on PATH.
  • Forgetting @version on remote installs.
  • Expecting go install to honor your go.mod for @version tools (it does not).
  • Expecting an -o flag (there is none).
  • Using @latest in CI and getting non-reproducible builds.
  • Looking for a cross-compiled binary in bin/ instead of bin/<os>_<arch>/.
  • Trying to install a library package (only main is installable).