add timer: timer function in bash

1 files changed, 39 insertions, 0 deletions

diff --git a/timer b/timer
new file mode 100755
index 0000000..e47bbcb
--- /dev/null
+++ b/timer
@@ -0,0 +1,39 @@
+#! /bin/bash
+#
+# Elapsed time.  Usage:
+#
+#   t=$(timer)
+#   ... # do something
+#   printf 'Elapsed time: %s\n' $(timer $t)
+#      ===> Elapsed time: 0:01:12
+#
+#
+#####################################################################
+# If called with no arguments a new timer is returned.
+# If called with arguments the first is used as a timer
+# value and the elapsed time is returned in the form HH:MM:SS.
+#
+function timer()
+{
+    if [[ $# -eq 0 ]]; then
+        echo $(date '+%s')
+    else
+        local  stime=$1
+        etime=$(date '+%s')
+
+        if [[ -z "$stime" ]]; then stime=$etime; fi
+
+        dt=$((etime - stime))
+        ds=$((dt % 60))
+        dm=$(((dt / 60) % 60))
+        dh=$((dt / 3600))
+        printf '%d:%02d:%02d' $dh $dm $ds
+    fi
+}
+
+# If invoked directly run test code.
+if [[ $(basename $0 .sh) == 'timer' ]]; then
+    t=$(timer)
+    read -p 'Enter when ready...' p
+    printf 'Elapsed time: %s\n' $(timer $t)
+fi