Add shebang to indicate bash requirement

Author: sdwheeler

reference/docs-conceptual/install/install-alpine.md

@@ -1,6 +1,6 @@
 ---
 description: How to install PowerShell on Alpine Linux
-ms.date: 12/15/2025
+ms.date: 02/04/2026
 title: Install PowerShell on Alpine Linux
 ---
 # Install PowerShell on Alpine Linux
@@ -28,6 +28,7 @@ to the package depends on the version of PowerShell you want to install.
 Then, in the terminal, execute the following shell commands to install PowerShell 7.4:
 
 ```sh
+#!/bin/bash
 # install the requirements
 sudo apk add --no-cache \
     ca-certificates \

reference/docs-conceptual/install/install-debian.md

@@ -1,6 +1,6 @@
 ---
 description: How to install PowerShell on Debian Linux
-ms.date: 12/15/2025
+ms.date: 02/04/2026
 title: Install PowerShell on Debian
 ---
 # Install PowerShell on Debian
@@ -31,6 +31,7 @@ Installing PowerShell from PMC is the preferred method of installation.
 > This script only works for supported versions of Debian.
 
 ```sh
+#!/bin/bash
 ###################################
 # Prerequisites
 
@@ -81,6 +82,7 @@ The following shell script downloads and installs the current release of PowerSh
 change the URL to download the version of PowerShell that you want to install.
 
 ```sh
+#!/bin/bash
 ###################################
 # Prerequisites
 

reference/docs-conceptual/install/install-rhel.md

@@ -1,6 +1,6 @@
 ---
 description: Information about installing PowerShell on Red Hat Enterprise Linux (RHEL)
-ms.date: 12/15/2025
+ms.date: 02/04/2026
 title: Installing PowerShell on Red Hat Enterprise Linux (RHEL)
 ---
 # Installing PowerShell on Red Hat Enterprise Linux (RHEL)
@@ -31,6 +31,7 @@ Installing PowerShell from PMC is the preferred method of installation.
 > This script only works for supported versions of RHEL that are published to PMC.
 
 ```sh
+#!/bin/bash
 ###################################
 # Prerequisites
 

reference/docs-conceptual/install/install-ubuntu.md

@@ -1,6 +1,6 @@
 ---
 description: Information about installing PowerShell on Ubuntu
-ms.date: 12/15/2025
+ms.date: 02/04/2026
 title: Installing PowerShell on Ubuntu
 ---
 # Installing PowerShell on Ubuntu
@@ -31,6 +31,7 @@ Installing PowerShell from PMC is the preferred method of installation.
 > This script only works for supported versions of Ubuntu.
 
 ```sh
+#!/bin/bash
 ###################################
 # Prerequisites
 
@@ -93,6 +94,7 @@ The following shell script downloads and installs the current preview release of
 change the URL to download the version of PowerShell that you want to install.
 
 ```sh
+#!/bin/bash
 ###################################
 # Prerequisites