go

---
syntax: bash
tags: [ golang, go ]
---
# To run the package in the current directory
go run .

# To run the package in the ./cmd/foo directory
go run ./cmd/foo/

# To fetch dependencies
go get github.com/foo/bar@v1.2.3
go get github.com/foo/bar@8e1b8d3

# Upgrade the dependency.
go get -u github.com/foo/bar

# Building an Executable.
go build -o=/tmp/foo . # Compile the package in the current directory
go build -o=/tmp/foo ./cmd/foo # Compile the package in the ./cmd/foo directory

# Build cache
go env GOCACHE # Check where your build cache is
go build -a -o=/tmp/foo . # Force all packages to be rebuilt
go clean -cache # Remove everything from the build cache


# Cross-Compilation
GOOS=linux GOARCH=amd64 go build -o=/tmp/linux_amd64/foo .
GOOS=windows GOARCH=amd64 go build -o=/tmp/windows_amd64/foo.exe .

# List of all supported OS/architectures
go tool dist list

# To show all the dependencies of the module
go list -m all

# To sho why is that a dependency?
go mod why -m golang.org/x/sys

# Clear module cache
go clean -modcache

# View simplified documentation for the strings package
go doc strings

# View full documentation for the strings package
go doc -all strings

# View documentation for the strings.Replace function
go doc strings.Replace

# View documentation for the database/sql.DB type
go doc sql.DB

# View documentation for the database/sql.DB.Query method
go doc sql.DB.Query

# View the source code for the strings.Replace function
go doc -src strings.Replace

# Run all tests in the current directory
go test .

# Run all tests in the current directory and sub-directories
go test ./...

# Run all tests in the ./foo/bar directory
go test ./foo/bar

# Testing with race detector
go test -race ./...

# Bypass the test cache when running tests
go test -count=1 ./...

# Delete all cached test results
go clean -testcache

# Run the test with the exact name TestFooBar
go test -v -run=^TestFooBar$ .

# Run tests whose names start with TestFoo
go test -v -run=^TestFoo .

# Run the Baz subtest of the TestFooBar test only
go test -v -run=^TestFooBar$/^Baz$ .

# Handy flag - skip long running tests
go test -short ./...

# Handy flag - don't run further tests after a failure.
go test -failfast ./... 


# Test all module dependencies.
go test all

# Stress testing
go test -run=^TestFooBar$ -count=500 .


# Upgrading the code to a New Go Release
go fix ./...

# Create a new Github issue for Go's standard library
go bug 


# Running and Comparing Benchmarks
go test -bench=. ./... # Run all benchmarks and tests
go test -run=^$ -bench=. ./... # Run all benchmarks (and no tests)
go test -run=^$ -bench=^BenchmarkFoo$ ./... # Run only the BenchmarkFoo benchmark (and no tests)
go test -bench=. -benchmem ./... # Forces the output of memory allocation statistics
go test -bench=. -benchtime=5s ./... # Run each benchmark test for at least 5 seconds
go test -bench=. -benchtime=500x ./... # Run each benchmark test for exactly 500 iterations
go test -bench=. -count=3 ./... # Repeat each benchmark test 3 times over
go test -bench=. -cpu=1,4,8 ./... # Run benchmarks with GOMAXPROCS set to 1, 4 and 8


# Comparing changes between benchmarks
go get golang.org/x/tools/cmd/benchcmp@latest # Install the compare tool.
go test -run=^$ -bench=. -benchmem ./... > /tmp/old.txt # Measure benchmark before changes
go test -run=^$ -bench=. -benchmem ./... > /tmp/new.txt # Measure benchmark after changes
benchcmp /tmp/old.txt /tmp/new.txt  # Compare changes.


# Using Compiler and Linker Flags
go tool compile -help # complete list of available compiler flags
go build -gcflags="-m -m" -o=/tmp/foo . # print optimization decisions
go build -gcflags="all=-m" -o=/tmp/foo . # optimization decisions for dependencies too
go build -gcflags="all=-N -l" -o=/tmp/foo . # disable optimizations and inlining
go tool link -help # list of available linker flags
go build -ldflags="-X main.version=1.2.3" -o=/tmp/foo . # add a version number
go build -ldflags="-s -w" -o=/tmp/foo . # strip debug information from the binary
CGO_ENABLED=0 GOOS=linux go build -a -ldflags '-extldflags "-static"' . # make the binary as static as possible


# Trace generation
go test -run=^$ -bench=^BenchmarkFoo$ -trace=/tmp/trace.out .
go tool trace /tmp/trace.out # Works only on Chrome / Chromium at the moment


# Viewing Environment Information
go env # List all environment variables.
go env -w GOPATH=/foo/bar # Set GOPATH environment variable to /foo/bar

# Checking for Race Conditions
go build -race -o=/tmp/foo . # not for production