diff --git a/reexec/command_linux.go b/reexec/command_linux.go
index 8dc3f3a..e22a023 100644
--- a/reexec/command_linux.go
+++ b/reexec/command_linux.go
@@ -7,6 +7,10 @@ import (
 	"syscall"
 )
 
+// Command returns *exec.Cmd which have Path as current binary. Also it setting
+// SysProcAttr.Pdeathsig to SIGTERM.
+// For example if current binary is "docker" at "/usr/bin", then cmd.Path will
+// be set to "/usr/bin/docker".
 func Command(args ...string) *exec.Cmd {
 	return &exec.Cmd{
 		Path: Self(),
diff --git a/reexec/command_unsupported.go b/reexec/command_unsupported.go
index 4adcd8f..630eecb 100644
--- a/reexec/command_unsupported.go
+++ b/reexec/command_unsupported.go
@@ -6,6 +6,7 @@ import (
 	"os/exec"
 )
 
+// Command is unsupported on operating systems apart from Linux and Windows.
 func Command(args ...string) *exec.Cmd {
 	return nil
 }
diff --git a/reexec/command_windows.go b/reexec/command_windows.go
index 124d42f..a2a7aa9 100644
--- a/reexec/command_windows.go
+++ b/reexec/command_windows.go
@@ -6,6 +6,9 @@ import (
 	"os/exec"
 )
 
+// Command returns *exec.Cmd which have Path as current binary.
+// For example if current binary is "docker.exe" at "C:\", then cmd.Path will
+// be set to "C:\docker.exe".
 func Command(args ...string) *exec.Cmd {
 	return &exec.Cmd{
 		Path: Self(),