Add a rebuild command as suggested by @AngerM in #1

README.md

diff --git a/README.md b/README.md
index b17f3e5..d46fb98 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,21 @@
 
 Full usage on [GoDoc ![GoDoc](https://godoc.org/github.com/FiloSottile/gvt?status.svg)](http://godoc.org/github.com/FiloSottile/gvt)
 
+## Alternative: not checking in vendored source
+
+Some developers prefer not to check in the source of the vendored dependencies. In that case you can add lines like these to e.g. your `.gitignore`
+
+    vendor/**
+    !vendor/manifest
+
+When you check out the source again, you can then run `gvt rebuild` to fetch all the dependencies at the revisions specified in the `vendor/manifest` file.
+
+Please consider that this approach has the following consequences:
+
+  * the package consumer will need gvt to fetch the dependencies
+  * the dependencies will need to remain available from the source repositories: if the original repository goes down or rewrites history, build reproducibility is lost
+  * `go get` won't work on your package
+
 ## Why
 
 There are many Go vendoring tools, but they all have some subset of the following problems

alldocs.go

diff --git a/alldocs.go b/alldocs.go
index b05f1c6..85e106b 100644
--- a/alldocs.go
+++ b/alldocs.go
@@ -10,6 +10,7 @@
 The commands are:
 
         fetch       fetch a remote dependency
+        rebuild     rebuild dependencies from manifest
         update      update a local dependency
         list        list dependencies one per line
         delete      delete a local dependency
@@ -42,6 +43,26 @@
 	-precaire
 		allow the use of insecure protocols.
 
+Rebuild dependencies from manifest
+
+Usage:
+        gvt rebuild
+
+rebuild fetches the dependencies listed in the manifest.
+
+It's meant for workflows that don't include checking in to VCS the vendored
+source, for example if .gitignore includes lines like
+
+    vendor/**
+    !vendor/manifest
+
+Note that such a setup requires "gvt rebuild" to build the source, relies on
+the availability of the dependencies repositories and breaks "go get".
+
+Flags:
+	-precaire
+		allow the use of insecure protocols.
+
 Update a local dependency
 
 Usage:

main.go

diff --git a/main.go b/main.go
index 89a8dc6..c95d30b 100644
--- a/main.go
+++ b/main.go
@@ -27,6 +27,7 @@
 
 var commands = []*Command{
 	cmdFetch,
+	cmdRebuild,
 	cmdUpdate,
 	cmdList,
 	cmdDelete,

rebuild.go

diff --git a/rebuild.go b/rebuild.go
new file mode 100644
index 0000000..9d4b0fa
--- /dev/null
+++ b/rebuild.go
@@ -0,0 +1,89 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/FiloSottile/gvt/gbvendor"
+)
+
+var (
+	rbInsecure bool // Allow the use of insecure protocols
+)
+
+func addRebuildFlags(fs *flag.FlagSet) {
+	fs.BoolVar(&rbInsecure, "precaire", false, "allow the use of insecure protocols")
+}
+
+var cmdRebuild = &Command{
+	Name:      "rebuild",
+	UsageLine: "rebuild",
+	Short:     "rebuild dependencies from manifest",
+	Long: `rebuild fetches the dependencies listed in the manifest.
+
+It's meant for workflows that don't include checking in to VCS the vendored
+source, for example if .gitignore includes lines like
+
+    vendor/**
+    !vendor/manifest
+
+Note that such a setup requires "gvt rebuild" to build the source, relies on
+the availability of the dependencies repositories and breaks "go get".
+
+Flags:
+	-precaire
+		allow the use of insecure protocols.
+`,
+	Run: func(args []string) error {
+		switch len(args) {
+		case 0:
+			return rebuild()
+		default:
+			return fmt.Errorf("rebuild takes no arguments")
+		}
+	},
+	AddFlags: addRebuildFlags,
+}
+
+func rebuild() error {
+	m, err := vendor.ReadManifest(manifestFile())
+	if err != nil {
+		return fmt.Errorf("could not load manifest: %v", err)
+	}
+
+	for _, dep := range m.Dependencies {
+		dst := filepath.Join(vendorDir(), dep.Importpath)
+		if _, err := os.Stat(dst); err == nil {
+			if err := vendor.RemoveAll(dst); err != nil {
+				// TODO need to apply vendor.cleanpath here too
+				return fmt.Errorf("dependency could not be deleted: %v", err)
+			}
+		}
+
+		log.Printf("fetching %s", dep.Importpath)
+
+		repo, _, err := vendor.DeduceRemoteRepo(dep.Importpath, rbInsecure)
+		if err != nil {
+			return err
+		}
+
+		wc, err := repo.Checkout("", "", dep.Revision)
+		if err != nil {
+			return err
+		}
+
+		src := filepath.Join(wc.Dir(), dep.Path)
+		if err := vendor.Copypath(dst, src); err != nil {
+			return err
+		}
+
+		if err := wc.Destroy(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}