UsageLine: "gopath",
Short: "GOPATH environment variable",
Long: `
+The Go path is used to resolve import statements.
+It is implemented by and documented in the go/build package.
+
The GOPATH environment variable lists places to look for Go code.
On Unix, the value is a colon-separated string.
On Windows, the value is a semicolon-separated string.
//
// Go Path
//
-// TODO: Document GOPATH.
+// The Go path is a list of directory trees containing Go source code.
+// It is consulted to resolve imports that cannot be found in the standard
+// Go tree. The default path is the value of the GOPATH environment
+// variable, interpreted as a path list appropriate to the operating system
+// (on Unix, the variable is a colon-separated string;
+// on Windows, a semicolon-separated string;
+// on Plan 9, a list).
+//
+// Each directory listed in the Go path must have a prescribed structure:
+//
+// The src/ directory holds source code. The path below 'src' determines
+// the import path or executable name.
+//
+// The pkg/ directory holds installed package objects.
+// As in the Go tree, each target operating system and
+// architecture pair has its own subdirectory of pkg
+// (pkg/GOOS_GOARCH).
+//
+// If DIR is a directory listed in the Go path, a package with
+// source in DIR/src/foo/bar can be imported as "foo/bar" and
+// has its compiled form installed to "DIR/pkg/GOOS_GOARCH/foo/bar.a"
+// (or, for gccgo, "DIR/pkg/gccgo/foo/libbar.a").
+//
+// The bin/ directory holds compiled commands.
+// Each command is named for its source directory, but only
+// using the final element, not the entire path. That is, the
+// command with source in DIR/src/foo/quux is installed into
+// DIR/bin/quux, not DIR/bin/foo/quux. The foo/ is stripped
+// so that you can add DIR/bin to your PATH to get at the
+// installed commands.
+//
+// Here's an example directory layout:
+//
+// GOPATH=/home/user/gocode
+//
+// /home/user/gocode/
+// src/
+// foo/
+// bar/ (go code in package bar)
+// x.go
+// quux/ (go code in package main)
+// y.go
+// bin/
+// quux (installed command)
+// pkg/
+// linux_amd64/
+// foo/
+// bar.a (installed package object)
//
// Build Constraints
//