diff --git a/.github/workflows/install.yml b/.github/workflows/install.yml
index e59b731f8..fbdb6d5aa 100644
--- a/.github/workflows/install.yml
+++ b/.github/workflows/install.yml
@@ -7,8 +7,8 @@ on:
     branches:
       - "**"
     paths:
-      - '.github/workflows/install.yml'
-      - 'src/bin/install'
+      - ".github/workflows/install.yml"
+      - "src/bin/install"
 
 jobs:
   install:
@@ -31,3 +31,9 @@ jobs:
 
       - name: Sanity check
         run: defang --version
+
+      - name: Install with bash (nightly)
+        shell: bash
+        run: bash <(curl -fsSL s.defang.io/install) nightly
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} # alt name
diff --git a/src/bin/install b/src/bin/install
old mode 100644
new mode 100755
index 1ac07d611..c1de34460
--- a/src/bin/install
+++ b/src/bin/install
@@ -1,3 +1,4 @@
+#!/bin/sh
 #######################################################################################
 #                                                                                     #
 # This script installs the latest release of Defang from GitHub. It is designed       #
@@ -8,8 +9,21 @@
 # This allows us to do some interactive stuff where we can prompt the user for input  #
 # and have the user run the defang executable from the updated PATH environment var.  #
 #                                                                                     #
+# Pin to a specific version using DEFANG_INSTALL_VERSION or:                          #
+#                                                                                     #
+# bash <(curl -fsSL s.defang.io/install) 3.5.2                                        #
+# curl -fsSL s.defang.io/install | sh -s -- v3.5.2                                    #
+# curl -fsSL s.defang.io/install | bash -s -- nightly                                 #
+#                                                                                     #
 #######################################################################################
 
+_defang_install() {
+local REPLY CI="${CI:-}"
+local RELEASE_PATH AUTH_HEADER RELEASE_JSON
+local ARCH OS ARCH_SUFFIX DOWNLOAD_URL FILENAME EXTRACT_DIR
+local INSTALL_DIR="${INSTALL_DIR:-}" BINARY_NAME
+local EXPORT_PATH FOUND_PROFILE_FILE CURRENT_SHELL
+
 echo "\
        __     ____
   ____/ /__  / __/___ _____  ____ _
@@ -19,16 +33,26 @@ echo "\
                           /____/
 "
 
-# Check for -y flag or CI var and set the REPLY variable to "y" if it is present
-if [[ "$1" == "-y" ]] || [[ "$CI" == "1" ]] || [[ "$CI" == "true" ]]; then
-    REPLY="y" # TODO: this will fail in Fish shell
+# Parse arguments: [-y] [version]
+for _arg in "$@"; do
+    if [ "$_arg" = "-y" ]; then
+        REPLY="y"
+        CI="1"
+    elif [ -z "$DEFANG_INSTALL_VERSION" ]; then
+        DEFANG_INSTALL_VERSION="$_arg"
+    fi
+done
+unset _arg
+
+if [ "$CI" = "1" ] || [ "$CI" = "true" ]; then
+    REPLY="y"
     CI="1"
 fi
 
 # check if DEFANG_INSTALL_VERSION is set and set the release path accordingly
-if [[ -z "$DEFANG_INSTALL_VERSION" ]]; then
+if [ -z "$DEFANG_INSTALL_VERSION" ]; then
     RELEASE_PATH="latest"
-elif [[ "$DEFANG_INSTALL_VERSION" == "nightly" ]]; then
+elif [ "$DEFANG_INSTALL_VERSION" = "nightly" ]; then
     RELEASE_PATH="tags/nightly"
 else
     RELEASE_PATH="tags/v${DEFANG_INSTALL_VERSION#v}"
@@ -37,16 +61,16 @@ fi
 # Anonymous API request to GitHub are rate limited to 60 requests per hour.
 # Check whether the user has set a GitHub token to increase the rate limit.
 AUTH_HEADER=""
-if [[ -n "$GITHUB_TOKEN" ]]; then
+if [ -n "$GITHUB_TOKEN" ]; then
     AUTH_HEADER="Authorization: Bearer $GITHUB_TOKEN"
-elif [[ -n "$GH_TOKEN" ]]; then
+elif [ -n "$GH_TOKEN" ]; then
     AUTH_HEADER="Authorization: Bearer $GH_TOKEN"
 fi
 
 # Echo fetching the release path either latest or the version
 echo "Fetching the ${RELEASE_PATH#tags/} release of defang..."
 # Download the release information from GitHub, using the token if available, but falling back to anonymous access
-RELEASE_JSON=$([[ -n "$AUTH_HEADER" ]] &&
+RELEASE_JSON=$([ -n "$AUTH_HEADER" ] &&
     curl -fsSL -H "$AUTH_HEADER" https://api.github.com/repos/DefangLabs/defang/releases/$RELEASE_PATH ||
     curl -fsSL https://api.github.com/repos/DefangLabs/defang/releases/$RELEASE_PATH)
 
@@ -177,27 +201,32 @@ _prompt_and_append_to_file() {
     echo
     echo "  $line"
     echo
-    if [[ "$CI" != "1" ]]; then
+    if [ "$CI" != "1" ]; then
         # Prompt the user for confirmation
-        echo -n "$prompt $profile_file? (y/n) "
+        printf "%s %s? (y/n) " "$prompt" "$profile_file"
         read REPLY
         echo    # move to a new line
     fi
-    if [[ $REPLY =~ ^[Yy]$ ]]; then
-        # Append the line to the profile file
-        echo >> "$profile_file"
-        echo "$line # Added by Defang install" >> "$profile_file"
-    else
-        # Print the command for the user to run manually
-        echo "To manually add the required line, run the following command:"
-        echo
-        echo "  echo '$line' >> \"$profile_file\""
-        echo
-    fi
+    case "$REPLY" in
+        [Yy])
+            # Append the line to the profile file
+            echo >> "$profile_file"
+            echo "$line # Added by Defang install" >> "$profile_file"
+            ;;
+        *)
+            # Print the command for the user to run manually
+            echo "To manually add the required line, run the following command:"
+            echo
+            echo "  echo '$line' >> \"$profile_file\""
+            echo
+            ;;
+    esac
 }
 
 # Add the installation directory to PATH if not already present
-if [[ ":$PATH:" != *":$INSTALL_DIR:"* ]]; then
+case ":$PATH:" in
+    *":$INSTALL_DIR:"*) ;;
+    *)
     echo "Adding $INSTALL_DIR to your PATH for this session."
     export PATH="$PATH:$INSTALL_DIR"
 
@@ -208,20 +237,21 @@ if [[ ":$PATH:" != *":$INSTALL_DIR:"* ]]; then
     FOUND_PROFILE_FILE=false
     for CURRENT_SHELL in bash zsh ksh; do
         # If the profile file exists in the user's home directory, add a line to it
-        if [[ -f "$HOME/.${CURRENT_SHELL}rc" ]]; then
+        if [ -f "$HOME/.${CURRENT_SHELL}rc" ]; then
             FOUND_PROFILE_FILE=true
             _prompt_and_append_to_file "Can we append the necessary line to" "$HOME/.${CURRENT_SHELL}rc" "$EXPORT_PATH"
         fi
     done
 
     # If no profile file was found
-    if [[ $FOUND_PROFILE_FILE == false ]]; then
+    if [ "$FOUND_PROFILE_FILE" = false ]; then
         # Get the name of the current shell
         CURRENT_SHELL="$(basename "${SHELL:-$0}")"
         # Prompt the user to create a new profile file
         _prompt_and_append_to_file "No existing profile file found. Can we create" "$HOME/.${CURRENT_SHELL}rc" "$EXPORT_PATH"
     fi
-fi
+    ;;
+esac
 
 # Usage: _generate_completion_script "shell" "path/to/completion/_script"
 _generate_completion_script() {
@@ -239,7 +269,7 @@ _install_completion_script() {
     case $shell in
         bash)
             _generate_completion_script $shell "$HOME/.local/share/bash-completion.d/defang" || return 11
-            if [[ -z "$BASH_COMPLETION_VERSINFO" ]]; then
+            if [ -z "$BASH_COMPLETION_VERSINFO" ]; then
                 echo "Warning: bash completions require package bash-completion to be installed."
                 return 14
             fi
@@ -247,9 +277,10 @@ _install_completion_script() {
             ;;
         zsh)
             _generate_completion_script $shell "$HOME/.local/share/zsh/site-functions/_defang" || return 12
-            if [[ ":$FPATH:" != *":$HOME/.local/share/zsh/site_functions:"* ]]; then
-                _prompt_and_append_to_file "Can we add shell completions to" "$HOME/$profile_file" "fpath=(\$HOME/.local/share/zsh/site-functions \$fpath)"
-            fi
+            case ":$FPATH:" in
+                *":$HOME/.local/share/zsh/site-functions:"*) ;;
+                *) _prompt_and_append_to_file "Can we add shell completions to" "$HOME/$profile_file" "fpath=(\$HOME/.local/share/zsh/site-functions \$fpath)" ;;
+            esac
             ;;
         *) return 13 ;;
     esac
@@ -257,7 +288,7 @@ _install_completion_script() {
 
 _install_completion_script $SHELL || true
 CURRENT_SHELL=${0#-}
-[[ $CURRENT_SHELL != $SHELL ]] && _install_completion_script $CURRENT_SHELL || true
+[ "$CURRENT_SHELL" != "$SHELL" ] && _install_completion_script $CURRENT_SHELL || true
 
 # Cleanup: Remove the temporary directory
 echo "Cleaning up..."
@@ -273,6 +304,9 @@ if [ -t 1 ] && [ "$CI" != "1" ] && [ "$CI" != "true" ]; then
     echo "Alternatively, you can use Defang's built-in agent by running '$BINARY_NAME'."
 fi
 
-# Unset the variables and functions to avoid polluting the user's environment
-unset EXTRACT_DIR DOWNLOAD_URL RELEASE_JSON RELEASE_PATH ARCH_SUFFIX ARCH OS FILENAME INSTALL_DIR BINARY_NAME REPLY EXPORT_PATH CURRENT_SHELL FOUND_PROFILE_FILE AUTH_HEADER
-unset -f _prompt_and_append_to_file _generate_completion_script _install_completion_script
+}
+
+_defang_install "$@"
+
+# Unset functions to avoid polluting the user's environment when sourcing the script
+unset -f _defang_install _prompt_and_append_to_file _generate_completion_script _install_completion_script 2>/dev/null