1 files changed, 65 insertions, 0 deletions
diff --git a/sw b/sw
new file mode 100755
index 0000000..3efdd0f
--- /dev/null
+++ b/sw
@@ -0,0 +1,65 @@
+#!/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 | 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