}

func ExampleExt() {
	fmt.Println(path.Ext("/a/b/c/bar.css"))
	fmt.Println(path.Ext("/"))
	fmt.Println(path.Ext(""))
	// Output:
	// .css
	//
	//
}

func ExampleIsAbs() {
	fmt.Println(path.IsAbs("/dev/null"))
	// Output: true
}

func ExampleJoin() {
	fmt.Println(path.Join("a", "b", "c"))
	fmt.Println(path.Join("a", "b/c"))
	fmt.Println(path.Join("a/b", "c"))

	// Run go list to find the location of every package we care about.
	pkgs := make(map[string]*Pkg)
	var list []string
	for _, profile := range profiles {
		if strings.HasPrefix(profile.FileName, ".") || filepath.IsAbs(profile.FileName) {
			// Relative or absolute path.
			continue
		}
		pkg := path.Dir(profile.FileName)
		if _, ok := pkgs[pkg]; !ok {
			pkgs[pkg] = nil
			list = append(list, pkg)
		}
	}

		path = path[i+1:]
	}
	// If empty now, it had only slashes.
	if path == "" {
		return "/"
	}
	return path
}

// IsAbs reports whether the path is absolute.
func IsAbs(path string) bool {
	return len(path) > 0 && path[0] == '/'
}

// Dir returns all but the last element of path, typically the path's directory.

		if dir == "" {
			// Unix shell semantics: path element "" means "."
			dir = "."
		}
		path := filepath.Join(dir, file)
		if err := findExecutable(path); err == nil {
			if !filepath.IsAbs(path) {
				if execerrdot.Value() != "0" {
					return path, &Error{file, ErrDot}
				}
				execerrdot.IncNonDefault()
			}
			return path, nil
		}
	}
	return "", &Error{file, ErrNotFound}
}

			return false
		}
	}
	return true
}

func toUpper(c byte) byte {
	if 'a' <= c && c <= 'z' {
		return c - ('a' - 'A')
	}
	return c
}

// IsAbs reports whether the path is absolute.
func IsAbs(path string) (b bool) {
	l := volumeNameLen(path)
	if l == 0 {
		return false
	}
	// If the volume name starts with a double slash, this is an absolute path.

	}
	cmd.Env = append(cmd.Environ(), fmt.Sprintf("%s=1", executable_EnvVar))
	out, err := cmd.CombinedOutput()
	if err != nil {
		t.Fatalf("exec(self) failed: %v", err)
	}
	outs := string(out)
	if !filepath.IsAbs(outs) {
		t.Fatalf("Child returned %q, want an absolute path", out)
	}
	if !sameFile(outs, ep) {
		t.Fatalf("Child returned %q, not the same file as %q", out, ep)
	}
}

func sameFile(fn1, fn2 string) bool {

	var dirFd = int32(-1)
	var dirName string

	dir := "/"
	if !isAbs(path) {
		dir = cwd
	}
	path = joinPath(dir, path)

	for _, p := range preopens {
		if len(p.name) > len(dirName) && stringslite.HasPrefix(path, p.name) {
			dirFd, dirName = p.fd, p.name
		}
	}

	path = path[len(dirName):]
	for isAbs(path) {
		path = path[1:]
	}
	if len(path) == 0 {
		path = "."
	}

	// otherwise distinguish between an explicit "off" and a UserCacheDir error.

	defaultDirOnce.Do(func() {
		defaultDir = cfg.Getenv("GOCACHE")
		if defaultDir != "" {
			defaultDirChanged = true
			if filepath.IsAbs(defaultDir) || defaultDir == "off" {
				return
			}
			defaultDir = "off"
			defaultDirErr = fmt.Errorf("GOCACHE is not an absolute path")
			return
		}

		// Compute default location.

	// If we didn't mount the subsystem, there is no point we make the path.
	if err != nil {
		return "", err
	}

	// If the cgroup name/path is absolute do not look relative to the cgroup of the init process.
	if filepath.IsAbs(cgroupPath) {
		// Sometimes subsystems can be mounted together as 'cpu,cpuacct'.
		return filepath.Join(root, mnt, cgroupPath), nil
	}

	parentPath, err := getCgroupV1ParentPath(mnt, root)
	if err != nil {

		if strings.HasPrefix(val, "~") {
			return fmt.Errorf("GOPATH entry cannot start with shell metacharacter '~': %q", val)
		}
		if !filepath.IsAbs(val) && val != "" {
			return fmt.Errorf("GOPATH entry is relative; must be absolute path: %q", val)
		}
	case "GOMODCACHE":
		if !filepath.IsAbs(val) && val != "" {
			return fmt.Errorf("GOMODCACHE entry is relative; must be absolute path: %q", val)
		}
	case "CC", "CXX":