#!/usr/bin/env bash set -e # Usage: # sw # - start a stopwatch from 0, save start time # sw [-r|--resume] # - start a stopwatch from the last saved start time (or current time if no last saved start time exists) # - "-r" stands for --resume function finish { tput cnorm # Restore cursor exit 0 } trap finish EXIT # Use GNU date if possible as it's most likely to have nanoseconds available. if hash gdate 2>/dev/null; then GNU_DATE=gdate elif date --version 2> /dev/null | grep 'GNU coreutils' >/dev/null; then GNU_DATE=date fi function datef { if [[ -z "$GNU_DATE" ]]; then date "$@" else $GNU_DATE "$@" fi } # Display nanoseconsd only if supported if datef +%N | grep -q N 2>/dev/null; then DATE_FORMAT="+%H:%M:%S" else DATE_FORMAT="+%H:%M:%S.%N" NANOS_SUPPORTED=true fi tput civis # hide cursor # If -r is passed, use saved start time from ~/.sw if [[ "$1" == "-r" || "$1" == "--resume" ]]; then if [[ ! -f $HOME/.sw ]]; then datef +%s > $HOME/.sw fi START_TIME=$(cat $HOME/.sw) else START_TIME=$(datef +%s) echo -n $START_TIME > $HOME/.sw fi # GNU date accepts the input date differently than BSD if [[ -z "$GNU_DATE" ]]; then DATE_INPUT="-v-${START_TIME}S" else DATE_INPUT="--date now-${START_TIME}sec" fi while [ true ]; do STOPWATCH=$(TZ=UTC datef $DATE_INPUT $DATE_FORMAT | ( [[ "$NANOS_SUPPORTED" ]] && sed 's/.\{7\}$//' || cat ) ) printf "\r\e%s" $STOPWATCH sleep 0.03 done