Additional help test when container.RunDir already exists

- Closes #1389

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

CHANGELOG.md

@@ -53,6 +53,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Correctly extract smbios asset key during Grub boot. #1291
 - Refactor of `wwinit/init` to more properly address rootfs options. #1098
 
+### Added
+
+- Additional help test when container.RunDir already exists. #1389
+
 ## v4.5.7, 2024-09-11
 
 ### Added

internal/app/wwctl/container/exec/main.go

@@ -4,7 +4,6 @@
 package exec
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"os/exec"
@@ -42,7 +41,7 @@ func runContainedCmd(cmd *cobra.Command, containerName string, args []string) (e
 	runDir := container.RunDir(containerName)
 	if err := os.Mkdir(runDir, 0750); err != nil {
 		if _, existerr := os.Stat(runDir); !os.IsNotExist(existerr) {
-			return errors.New("run directory already exists: another container command may already be running")
+			return fmt.Errorf("run directory already exists: another container command may already be running (otherwise, remove %s)", runDir)
 		} else {
 			return fmt.Errorf("unable to create run directory: %w", err)
 		}