backup.sh - log with timestamps

templates/docker-compose/borgmatic/backup.sh

@@ -12,13 +12,31 @@ LOGFILE="/tmp/backup_run_$(date +%s).log"
 SUCCESS_PREFIX="=?utf-8?Q? =E2=9C=85 SUCCESS?="
 FAILED_PREFIX="=?utf-8?Q? =E2=9D=8C FAILED?="
 
+# Helper function to prepend a timestamp and the first parameter to every line of STDIN
+_indent() {
+    while read -rs line; do
+	printf "%s%s\n" "$(date +%s)" "$1" "$line"
+    done
+}
+
+# This function prepends timestamps to stderr and stdout of the
+# command supplied as parameters to this.
+log() {
+    # Adapted from https://stackoverflow.com/a/31151808
+    {
+	"$@"   2>&1 1>&3 3>&- | _indent " ! "
+    } 3>&1 1>&2 | _indent " | " >>"$LOGFILE"
+}
+
 report() {
     if [ -n "$SUCCESS" ]; then
+	log echo SUCCESS
         PREFIX="$SUCCESS_PREFIX"
     else
+	log echo FAILED
         PREFIX="$FAILED_PREFIX"
     fi
-    echo -e "Subject: $PREFIX: $MAIL_SUBJECT\n\n$(cat $LOGFILE)\n" |
+    printf "Subject: $PREFIX: $MAIL_SUBJECT\n\n$(cat $LOGFILE)\n" |
         sendmail -t "$MAIL_TO"
 }
 
@@ -28,7 +46,7 @@ testmail() {
 }
 
 failed() {
-    echo "Exited abnormally!"
+    log echo "Exited abnormally!"
     report
     rm -f "$LOGFILE"
 }
@@ -50,7 +68,9 @@ if [ -n "$TEST_SMTP" ]; then
     exit
 fi
 
-if $BACKUP_COMMAND 2>&1 | tee "$LOGFILE"; then
+
+echo "STARTED" >> "$LOGFILE"
+if log $BACKUP_COMMAND; then
     SUCCESS=1
     report
 fi