send notification by email when holiday CSV has been updated

update

@@ -2,6 +2,10 @@
 
 # Settings
 CSV_URL="https://www8.cao.go.jp/chosei/shukujitsu/syukujitsu.csv"
+MAIL_TO="$USER"
+MAIL_FROM="info@holiday.kareha.org"
+MAIL_SUBJECT="Holiday CSV Updated"
+MAIL_BODY="Holiday CSV file has been Updated."
 
 # Constants
 EXIT_SUCCESS=0
@@ -18,6 +22,7 @@ verify_command() {
 verify_command "curl"
 verify_command "nkf"
 verify_command "awk"
+verify_command "mailx"
 
 # Logging
 CURRENT_MONTH=$(date "+%Yw%U%z")
@@ -35,6 +40,13 @@ log() {
   echo "$timestamp $message" >>$LOG_FILE
 }
 
+send_mail() {
+  echo "$MAIL_BODY" | mailx -r "$MAIL_FROM" -s "$MAIL_SUBJECT" "$MAIL_TO"
+  if [ $? -ne 0 ]; then
+    log "Failed to send email"
+  fi
+}
+
 # Acquire the lock or exit
 LOCK_DIR="lock"
 if ! mkdir "$LOCK_DIR" 2>/dev/null; then
@@ -58,6 +70,7 @@ if ! diff -q $RAW_CSV_FILE $TMP_CSV_FILE >/dev/null 2>&1; then
   current_year=$(date +'%Y')
   tail -n +2 $ALL_CSV_FILE | awk -v cy="$current_year" -F'/' '{ if ($1 >= cy) print }' >$CSV_FILE
   log "Changed"
+  send_mail
 else
   log "No Change"
   rm $TMP_CSV_FILE