Use enviornment bash. Use -n for snap check

scripts/images.sh

@@ -1,9 +1,11 @@
+#!/usr/bin/env bash
+
 function initImageVars {
     if [ "$(uname -s)" == "Linux" ]; then
         if [ "$ARCH" == "arm64" ]; then
             EFI_1="$SNAP/usr/share/qemu/edk2-aarch64-code.fd"
             EFI_2="$SNAP/usr/share/qemu/edk2-arm-vars.fd"
-            if [ "$SNAP" == "" ]; then
+            if [ -n "$SNAP" ]; then
                 QEMU=qemu-system-aarch64
             else
                 QEMU="$SNAP/usr/bin/qemu-system-aarch64"
@@ -15,7 +17,7 @@ function initImageVars {
                 -device AC97 \
                 -serial mon:stdio"
         else
-            if [ "$SNAP" == "" ]; then
+            if [ -n "$SNAP" ]; then
                 QEMU=qemu-system-x86_64
             else
                 QEMU="$SNAP/usr/bin/qemu-system-x86_64"

scripts/mounts.sh

@@ -1,3 +1,5 @@
+#!/usr/bin/env bash
+
 function initSettingsVars {
     if [ "$(uname -s)" == "Darwin" ]; then
         SETTINGS_FILE="$DATA_ROOT/sshd/settings.dmg"
@@ -57,7 +59,7 @@ function copySettingsIntoImage {
 
 function startVirtiofsd {
     # Return immediately in non-Snap environments
-    if [ "$SNAP" == "" ]; then
+    if [ -n "$SNAP" ]; then
         return
     fi
     VIRTIOFS_SOCK="$SNAP_USER_DATA/$NAME-vhost-fs.sock"

scripts/prerequisites.sh

@@ -11,7 +11,7 @@ if [ "$HOST_OS" == "Darwin" ]; then
     brew install coreutils
 elif [ "$HOST_OS" == "Linux" ]; then
     # Only necessary in non-Snap environments
-    if [ "$SNAP" == "" ]; then
+    if [ -n "$SNAP" ]; then
         sudo snap install --edge qemu-ut-pdk
         sudo snap connect qemu-ut-pdk:kvm
         # Heck, throw a group check in there too

scripts/setup.sh

@@ -1,6 +1,8 @@
+#!/usr/bin/env bash
+
 function warnMissingPlugs {
     # Only run in Snap environments
-    if [ "$SNAP" == "" ]; then
+    if [ -n "$SNAP" ]; then
         return
     fi
 
@@ -149,7 +151,7 @@ function setup {
 
     # Snap is done here, just needs ta check inside ya sshd settings
     # (on other platforms)
-    if [ "$SNAP" == "" ]; then
+    if [ -n "$SNAP" ]; then
         if [ -f "$DATA_ROOT/sshd/id_rsa" ]; then
             rm "$DATA_ROOT/sshd/id_rsa"
         fi

ubuntu-touch-pdk

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e