Language cheatsheet

Go 1 Cheatsheet

The go command for modules, building, testing and cross-compiling, plus the code patterns you write every day.

Setup and running

Check the Go version — Print the installed Go toolchain version.
Show Go environment settings — Print one environment setting, here the module cache and workspace location.
Start a module — Create a go.mod file. Use the path where the module will be published as its name.
Run the program — Compile and run the main package in the current folder.
Build a binary — Compile the package into an executable named myapp.
Install a command-line tool — Build and install a program from a module into your Go bin folder.

Add a dependency — Add a module at its latest version to go.mod.
Tidy go.mod — Add missing modules and remove unused ones. Run it after changing imports.
Download all dependencies — Download modules to the module cache, as CI and Docker builds do.
Update all dependencies — Upgrade the dependencies of your packages to their newest minor or patch versions.
See available updates — List modules that have newer versions.
Find out why a module is needed — Show the import chain that requires a module.
Print the dependency graph — Print each module and the modules it requires.
Use a local copy of a module — Point a dependency at a folder on disk while you develop it.
Vendor dependencies — Copy dependencies into a vendor folder for reproducible offline builds.
Create a workspace — Work on several modules together without editing their go.mod files.

Run all tests — Run the tests in every package of the module.
Run tests verbosely — Print the name and result of every test.
Run matching tests — Run tests whose names match a regular expression, in one package.
Detect data races — Run the tests with the race detector turned on.
Bypass the test cache — Run tests again even if nothing changed.
Measure coverage — Print the percentage of statements covered by tests.
View coverage in the browser — Write a coverage profile and open an annotated HTML report.
Run benchmarks — Run benchmarks and report memory allocations. Tests are skipped.
Fuzz a function — Run a fuzz test for 30 seconds to look for inputs that make it fail.
Profile a running service — Capture 30 seconds of CPU profile from a service that exposes net/http/pprof.

Format the code — Rewrite files in the standard Go style.
Find likely mistakes — Report suspicious constructs such as wrong Printf formats.
Read documentation — Show the documentation for a package or symbol in the terminal.
Run code generators — Run //go:generate directives found in the source.
Cross-compile for Linux — Build for another operating system and architecture.
Build a small static binary — Disable cgo and strip debug information for a compact, portable binary.
Set a version at build time — Set a string variable in package main from the command line.
Clear the build cache — Delete cached build results, for example to rule out stale artifacts.

Hello world — The smallest runnable Go program.
HTTP server — Start a web server with only the standard library, using method and path patterns in the router.
Handle and wrap errors — Return errors, wrapping them with context so callers can inspect the cause with errors.Is and errors.As.
Run goroutines and wait — Start work concurrently and wait for all of it to finish.
Set a timeout with context — Cancel an operation if it takes longer than five seconds.
Table-driven test — Run many cases through one test function, each as a named subtest.

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