cron job tweaks

cron.sh

@@ -1,6 +1,9 @@
 #!/bin/bash
 set -euo pipefail
 
+# install me in your crontab!
+# 0 5 1-25 12 *     $HOME/adventofcode2023/cron.sh auto
+
 year=2023
 root=~/adventofcode${year}
 
@@ -40,7 +43,11 @@ if test -e "$dir"; then
     exit 1
 fi
 
-cwd=${PWD:-`pwd`}
+if ! test -e "$root/cookie"; then
+    echo >&2 "warning: cookiefile '$root/cookie' not found. consider creating it"
+fi
+
+cwd=${PWD:-$(pwd)}
 mkdir "$dir"
 cd "$dir" || exit 1