feat: Show download progress (#608)

src/progress.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+
+escape () {
+    local s
+    s=${1//&/\&}
+    s=${s//</\&lt;}
+    s=${s//>/\&gt;}
+    s=${s//'"'/\&quot;}
+    printf -- %s "$s"
+    return 0
+}
+
+file="$1"
+body=$(escape "$2")
+info="/run/shm/msg.html"
+
+if [[ "$body" == *"..." ]]; then
+  body="<p class=\"loading\">${body/.../}</p>"
+fi
+
+while true
+do
+  if [ -f "$file" ]; then
+    bytes=$(du -sb "$file" | cut -f1)
+    if (( bytes > 1000 )); then
+      size=$(echo "$bytes" | numfmt --to=iec --suffix=B  | sed -r 's/([A-Z])/ \1/')
+      echo "${body//(\[P\])/($size)}"> "$info"
+    fi
+  fi
+  sleep 1
+done