Add script to compute number of files changed per weekday

Author: kgryte

tools/git/scripts/files_changed_per_weekday

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+#
+# Prints the number of files changed per weekday.
+
+# Determine root directory:
+root="$(git rev-parse --show-toplevel)"
+
+# Define the path to a utility to generate commit short stats:
+shortstats="${root}/tools/git/scripts/shortstats"
+
+# * `shortstats`
+#   - Get summary statistics for each commit.
+# * `awk '{}'`
+#   - Extract the commit timestamp and number of files changed.
+# * `perl -pe ''`
+#   - Convert each Unix timestamp to a date string.
+# * `awk '{}'`
+#   - Tabulate the weekday totals.
+"${shortstats}" | awk '{print $1 OFS $4}' | perl -pe 's/(\d+)/gmtime($1)/e' | awk '
+BEGIN {
+	split("Mon Tue Wed Thu Fri Sat Sun", days);
+}
+{
+	lines[$1] += $6
+}
+END {
+	for ( i = 1; i <= 7; i++ ) {
+		print days[i] OFS lines[days[i]]
+	}
+}'