Toolchain Commands

go run ./cmd/svc          # build and run, no binary kept
go build ./...            # compile everything
go test ./...             # run every test
go vet ./...              # static checks the compiler does not make
go fmt ./...              # canonical formatting; not negotiable
go fix ./...              # modernise to current idioms (rebuilt in Go 1.26)
go doc net/http Server    # docs for one identifier
go doc -src sync.Once Do  # its source, in the terminal
go env GOROOT             # where the standard library lives

go mod init github.com/you/svc
go mod tidy                        # add what is imported, drop what is not
go mod why example.com/pkg         # why is this in the graph
go mod graph                       # the whole requirement graph
go get example.com/pkg@v1.5.0      # change a requirement
go get -u ./...                    # upgrade, deliberately

go test ./...                     # cached
go test -count=1 ./...            # defeat the cache
go test -v -run 'TestParse/empty' # one subtest
go test -race ./...               # data race detector
go test -cover ./...              # coverage
go test -fuzz=FuzzRoundTrip       # open-ended fuzzing

func BenchmarkParse(b *testing.B) {
    for b.Loop() {            // Go 1.24; setup runs once, results kept alive
        Parse("1h30m")
    }
}

go test -bench=. -benchmem -count=10 ./... > old.txt
go test -bench=. -benchmem -count=10 ./... > new.txt
benchstat old.txt new.txt
go install golang.org/x/perf/cmd/benchstat@latest

go test -bench=. -cpuprofile=cpu.out -memprofile=mem.out ./...
go tool pprof cpu.out
go tool pprof -http=:8080 cpu.out             # flame graph in the browser
go tool pprof http://localhost:6060/debug/pprof/profile?seconds=30

go build -gcflags='-m' ./... 2>&1 | grep escapes
go build -gcflags='-m -m' ./...        # the reasoning chain

CGO_ENABLED=0 GOOS=linux GOARCH=arm64 go build \
  -trimpath \
  -ldflags="-s -w -X main.version=$(git describe --tags --always)" \
  -o bin/svc ./cmd/svc

go install golang.org/x/vuln/cmd/govulncheck@latest
govulncheck ./...     # reachability-aware, so the output is short enough to act on