Add USAGE information to burn-nixos.sh

1 files changed, 30 insertions, 3 deletions

diff --git a/scripts/burn-nixos.sh b/scripts/burn-nixos.sh
index 7518c1e..43903d7 100755
--- a/scripts/burn-nixos.sh
+++ b/scripts/burn-nixos.sh
@@ -1,10 +1,37 @@
 #!/usr/bin/env bash
 set -Eeuo pipefail
 
-NIXOS_URL="$1"
-USB_STICK="$2"
+usage() {
+  red "Missing argument $1."
+  cat <<EOF
+Usage:
+    burn-nixos.sh <NIXOS_URL> <USB_STICK>
+
+      Arguments:
+        NIXOS_URL         Download URL for NixOS ISO to be installed. Can be found at https://nixos.org/nixos/download.html
+        USB_STICK         File descriptor of USB stick where to burn the ISO into. Use lsblk or similar tools to get it's name.
+
+Examples:
+    Download NixOS 19.03 x86_64 and burn it into stick on /dev/sdb:
+        NIXOS_URL='https://releases.nixos.org/nixos/19.03/nixos-19.03.172764.50d5d73e22b/nixos-minimal-19.03.172764.50d5d73e22b-x86_64-linux.iso'
+        burn-nixos.sh "\$NIXOS_URL" /dev/sdb
+EOF
+}
+
+NIXOS_URL="${1:-}"
+USB_STICK="${2:-}"
 ISO_PATH='/tmp/nixos.iso'
 
+[[ -z "${NIXOS_URL}" ]] && {
+  usage 'NIXOS_URL'
+  exit 2
+}
+
+[[ -z "${USB_STICK}" ]] && {
+  usage 'USB_STICK'
+  exit 2
+}
+
 yellow "Downloading NixOS ISO..."
 wget -O "${ISO_PATH}"     "${NIXOS_URL}"
 wget -O "${ISO_PATH}.sha256" "${NIXOS_URL}.sha256"
@@ -16,6 +43,6 @@ green "Done. SHA256 match."
 
 yellow "Writing ISO image to ${USB_STICK}. We'll need sudo for it..."
 umount "${USB_STICK}1" ||:
-ls -lahp --color "${ISO_PATH}"
+blue "$(du -hs /tmp/nixos.iso)"
 sudo dd if="${ISO_PATH}" of="${USB_STICK}" status=progress
 green "Done. You can remove the USB stick ${USB_STICK} with no unmounting required."