bash last month

diff --git a/bash/last-month.sh b/bash/last-month.sh
new file mode 100644 (file)
index 0000000..4df75c2
--- /dev/null
+++ b/bash/last-month.sh
@@ -0,0 +1,24 @@
+#!/bin/bash
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the COMMON DEVELOPMENT AND DISTRIBUTION LICENSE
+#
+# You should have received a copy of the
+# COMMON DEVELOPMENT AND DISTRIBUTION LICENSE (CDDL) Version 1.0
+# along with this program.  If not, see http://www.sun.com/cddl/cddl.html
+
+# 2019 http://www.bananas-playground.net
+
+
+# last month problem
+# info date
+# The fuzz in units can cause problems with relative items.
+# For example, `2003-07-31 -1 month' might evaluate to 2003-07-01,
+# because 2003-06-31 is an invalid date.
+# To determine the previous month more reliably, you can ask for the month before the 15th of the current month.
+
+LAST_MONTH=`date -d "$(date +%Y-%m-15) -1 month" +%Y-%m`
+
+echo $LAST_MONTH
+
+exit 0;
\ No newline at end of file