some use cases in the help

reporting/timer

@@ -4,6 +4,17 @@ function helpexit() {
     echo "Simple Timer."
     echo '$PREFIX is printed before the time'
     echo '$POSTFIX is printed after the time'
+    echo 'Reset timer with kill -10'
+    echo '
+
+# use cases:
+#  timer | sleep 10
+#
+#  timer &
+#  sleep 10; kill -10 %1; sleep 5; kill %1
+#
+#  PREFIX=$'"'"'\033[33;1m'"'"' POSTFIX=$'"'"'\033[0m'"'"' timer | sleep 5
+'
     exit
 }
 
@@ -25,9 +36,31 @@ function displaytime {
   printf '%02d:%02d]%s\r' $M $S $POSTFIX
 }
 
-while true; do
+function finish_up {
   displaytime "$SECONDS" >&2
-  sleep 1
+  echo "" >&2
+  exit
+}
+
+function reset {
+  STARTED=$SECONDS
+}
+
+trap finish_up EXIT 9 15
+trap reset 10
+
+STARTED=$SECONDS
+while true; do
+  # Were in terminal
+  if [[ -t 1 ]]; then printf '\033[s'; fi
+  displaytime $(( SECONDS - STARTED )) >&2
+  if [[ -t 1 ]]; then printf '\033[u'; fi
   # die if parent dies
-  kill -0 $PPID 2>/dev/null || exit
+  kill -0 $PPID 2>/dev/null || { exit; }
+  # if stdout is pipe, print time there
+  # if pipe dies, timer dies too
+  if [[ ! -t 1 ]]; then displaytime "$SECONDS"; fi
+  sleep 1
 done
+
+