From 9409c06e326ad00dd99fca77d4caf0abeeabde93 Mon Sep 17 00:00:00 2001
From: Kroese <kroese@users.noreply.github.com>
Date: Sun, 19 Jul 2026 00:33:00 +0200
Subject: [PATCH] feat: Add post-install command support (#1887)

---
 docs/environment.md |  5 +++--
 readme.md           | 17 ++++++++++++-----
 src/define.sh       | 28 ++++++++++++++++++++++------
 3 files changed, 37 insertions(+), 13 deletions(-)

diff --git a/docs/environment.md b/docs/environment.md
index d2a669f4..0778dd6d 100644
--- a/docs/environment.md
+++ b/docs/environment.md
@@ -17,7 +17,6 @@ An empty default means the variable is unset and its value is determined automat
 | `PASSWORD` | `admin` | Password for the Windows account. |
 | `DOMAIN` |  | Active Directory domain to join during installation. |
 | `KEY` |  | Windows product key used to install and activate Windows. |
-| `MANUAL` | `N` | Enables manual installation instead of unattended installation. |
 
 ## 🧠 CPU and Memory
 
@@ -146,7 +145,7 @@ Also see [Dynamic memory allocation](https://github.com/qemus/qemu/blob/master/d
 | `BALLOONING_INTERVAL` | `5` | Polling interval in seconds. |
 | `BALLOONING_DEBUG` | `N` | Enables debug output for the ballooning monitor. |
 
-## 💿 Installation Media
+## 💿 Installation
 
 | Variable | Default | Description |
 |---|---|---|
@@ -154,6 +153,8 @@ Also see [Dynamic memory allocation](https://github.com/qemus/qemu/blob/master/d
 | `ESD` | `Y` | Enables downloading Windows through the ESD-based installation method. |
 | `VERIFY` | `N` | Verifies downloaded installation media against predefined checksums. |
 | `REMOVE` | `Y` | Deletes the downloaded Windows ISO after installation to save space. |
+| `MANUAL` | `N` | Enables manual installation instead of unattended installation. |
+| `COMMAND` |  | Command to be executed during the final step of automatic installation. |
 
 ## 🔌 Shutdown
 
diff --git a/readme.md b/readme.md
index 33bdf02d..ba421fff 100644
--- a/readme.md
+++ b/readme.md
@@ -272,18 +272,25 @@ kubectl apply -f https://raw.githubusercontent.com/dockur/windows/refs/heads/mas
 
   Replace the example path `./example.iso` with the filename of your desired ISO file. The value of `VERSION` will be ignored in this case.
 
-### How do I run a script after installation?
+### How do I run a command after installation?
+
+  To execute a single command during the final step of the automatic installation, add the `COMMAND` environment variable:
+
+  ```yaml
+  environment:
+    COMMAND: 'reg add "HKLM\Software\Example" /v Enabled /t REG_DWORD /d 1 /f'
+  ```
+
+  To run a script or include additional files, create a file called `install.bat` and place it in a folder together with any files it needs, such as software to be installed.
 
-  To run your own script after installation, you can create a file called `install.bat` and place it in a folder together with any additional files it needs (software to be installed for example).
-  
   Then bind that folder in your compose file like this:
 
   ```yaml
   volumes:
-    -  ./example:/oem
+    - ./example:/oem
   ```
 
-  The example folder `./example` will be copied to `C:\OEM` and the `install.bat` file inside that folder will be executed during the last step of the automatic installation.
+  The example folder `./example` will be copied to `C:\OEM` and the `install.bat` file inside it will be executed during the final step of the automatic installation.
 
 ### How do I perform a manual installation?
 
diff --git a/src/define.sh b/src/define.sh
index f60a4b11..4b369a04 100644
--- a/src/define.sh
+++ b/src/define.sh
@@ -1347,23 +1347,39 @@ validVersion() {
 addFolder() {
 
   local src="$1"
-  local folder="/oem"
+  local folder="/oem" file=""
+  local dest="$src/\$OEM\$/\$1/OEM"
 
   [ ! -d "$folder" ] && folder="/OEM"
   [ ! -d "$folder" ] && folder="$STORAGE/oem"
   [ ! -d "$folder" ] && folder="$STORAGE/OEM"
-  [ ! -d "$folder" ] && return 0
+  [ ! -d "$folder" ] && folder=""
 
-  local msg="Adding OEM folder to image..."
+  [ -z "$folder" ] && [ -z "$COMMAND" ] && return 0
+
+  local msg="Adding OEM files to image..."
   info "$msg" && html "$msg"
 
-  local dest="$src/\$OEM\$/\$1/OEM"
   mkdir -p "$dest" || return 1
-  cp -Lr "$folder/." "$dest" || return 1
 
-  local file
+  if [ -n "$folder" ]; then
+    cp -Lr "$folder/." "$dest" || return 1
+  fi
+
   file=$(find "$dest" -maxdepth 1 -type f -iname install.bat -print -quit) || return 1
 
+  if [ -n "$COMMAND" ]; then
+
+    [ -z "$file" ] && file="$dest/install.bat"
+
+    if [ -s "$file" ]; then
+      printf '\n' >> "$file" || return 1
+    fi
+
+    printf '%s\n' "$COMMAND" >> "$file" || return 1
+
+  fi
+
   if [ -f "$file" ]; then
     if ! unix2dos -q "$file"; then
       error "Failed to convert $file to DOS format!"