Fix envsubstr installation in Devbox

For users using devbox directly on their machines, envsubstr is now installed in the isolated devbox environment. Thus not conflicting with the GNU system installation.

Fix the below clusterawsadm installation error when re-entering the devbox environment
"ln: failed to create symbolic link '$INSTALL_DIR/clusterawsadm': File exists"

Author: spandan541

scripts/devbox-init-hook.sh

@@ -2,29 +2,16 @@
 DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 SRC_DIR="$(dirname $DIR)"
 
-# Set install path
-INSTALL_DIR="$HOME/.local/bin"
-mkdir -p "$INSTALL_DIR"
-
-# Check if envsubst.old exists
-if [[ ! -f "/usr/bin/envsubst.old" ]]; then
-    echo "envsubst.old does not exist. Proceeding with installation..."
+# Set install path to devbox packages directory
+INSTALL_DIR="$DEVBOX_PACKAGES_DIR/bin"
 
+if [[ ! -f "$INSTALL_DIR/envsubst" ]]; then
     ENVSUBST_VERSION="v1.4.3"
     URL="https://github.com/a8m/envsubst/releases/download/$ENVSUBST_VERSION/envsubst-$(uname -s)-$(uname -m)"
     echo "Downloading: $URL"
-
-    curl -sL $URL -o $INSTALL_DIR/envsubst
-    chmod +x "$INSTALL_DIR/envsubst"
-
-    # Replace existing envsubst if present
-    if [[ -f "/usr/bin/envsubst" ]]; then
-        sudo mv /usr/bin/envsubst /usr/bin/envsubst.old
-        sudo ln -s "$INSTALL_DIR/envsubst" /usr/bin/envsubst
-        echo "Replaced existing envsubst with the new one at /usr/bin/envsubst"
-    else
-        touch /usr/bin/envsubst.old
-    fi
+    echo "Installing github.com/a8m/envsubst into Devbox shell"
+    sudo curl -sL $URL -o $INSTALL_DIR/envsubst
+    sudo chmod +x "$INSTALL_DIR/envsubst"
 
     # Verify installation
     if ! command -v envsubst &>/dev/null; then
@@ -34,8 +21,7 @@ if [[ ! -f "/usr/bin/envsubst.old" ]]; then
 fi
 
 # Use build location by default
-if [[ ! -e "$INSTALL_DIR/clusterawsadm" ]]; then
+if [[ ! -L "$INSTALL_DIR/clusterawsadm" ]]; then
     echo "Linking [$SRC_DIR/bin/clusterawsadm] [$INSTALL_DIR/clusterawsadm]"
-    mkdir -p "$INSTALL_DIR"
-    ln -s "$SRC_DIR/bin/clusterawsadm" $INSTALL_DIR/clusterawsadm
+    sudo ln -s "$SRC_DIR/bin/clusterawsadm" $INSTALL_DIR/clusterawsadm
 fi