calculating command's execution time

plugins/timer/timer.plugin.zsh

+preexec() {
+  __timer_cmd_start_time=$(date '+%s')
+}
+
+precmd() {
+  if [ -n "${__timer_cmd_start_time}" ]; then
+    local cmd_end_time=$(date '+%s')
+    local tdiff=$((${cmd_end_time} - ${__timer_cmd_start_time}))
+    unset __timer_cmd_start_time
+    local tdiffstr='/'
+    if (( tdiff >= 60 )); then
+      tdiffstr+="$((tdiff / 60))m"
+    fi
+    tdiffstr+="$((tdiff % 60))s"
+    local cols=$(($COLUMNS - ${#tdiffstr} - 1))
+    echo -e "\033[1A\033[${cols}C ${tdiffstr}"
+  fi
+}