Shell Scripting Examples

Generate comma separated dates for last seven days:

# Fetch the date 7 days ago
DATE=$(date -d '7 day ago' '+%Y-%m-%d');

# Generate comma-separated string for last 7 days
for i in {6..1}; do DATE=$DATE","$(date -d "$i day ago" '+%Y-%m-%d'); done

Considering current date is 2016-04-08, DATE variable value will be as follows:

2016-04-01,2016-04-02,2016-04-03,2016-04-04,2016-04-05,2016-04-06,2016-04-07

We can use different date formats on a case to case basis. This thing comes in handy when we have to feed a date range to some reporting tool.

Generate comma separated dates for last month and from today to start of the day:

	# This script generate comma separated dates for last month in yyyy-mm-dd format.
	# Ex:
	# "2018-04-01,2018-04-02,2018-04-03,2018-04-04,2018-04-05,2018-04-06,2018-04-07,
	# 2018-04-08,2018-04-09,2018-04-10,2018-04-11,2018-04-12,2018-04-13,2018-04-14,
	# 2018-04-15,2018-04-16,2018-04-17,2018-04-18,2018-04-19,2018-04-20,2018-04-21,
	# 2018-04-22,2018-04-23,2018-04-24,2018-04-25,2018-04-26,2018-04-27,2018-04-28,
	# 2018-04-29,2018-04-30"
	set `date +%m" "%Y`
	CURMTH=$1
	CURYR=$2
	if [ $CURMTH -eq 1 ]
	then
	PRVMTH=12
	PRVYR=`expr $CURYR - 1`
	else
	PRVMTH=`expr $CURMTH - 1`
	PRVYR=$CURYR
	fi
	if [ $PRVMTH -lt 10 ]
	then PRVMTH="0"$PRVMTH
	fi
	LASTDY=`cal $PRVMTH $PRVYR | egrep "28|29|30|31" |tail -1 |awk '{print $NF}'`
	FROM_DATE="$PRVYR-$PRVMTH-01"
	TO_DATE="$PRVYR-$PRVMTH-$LASTDY"
	# convert in seconds sinch the epoch:
	start=$(date -d$FROM_DATE +%s)
	end=$(date -d$TO_DATE +%s)
	cur=$start
	while [ $cur -le $end ]; do
	# convert seconds to date:
	REPORT_DATE=$REPORT_DATE$(date -d@$cur +%Y-%m-%d)",";
	let cur+=24*60*60
	done
	# Remove last comma (,)
	REPORT_DATE=${REPORT_DATE::-1}
	echo $REPORT_DATE;

view raw generate-dates-for-last-month.sh hosted with ❤ by GitHub

	# This script generates the dates from today till the start of the month in yyyy-mm-dd format.
	# Ex. If current date is 2018-05-03 then it will generate "2018-05-01,2018-05-02,2018-05-03".
	set `date +%m" "%Y`
	CURMTH=$1
	CURYR=$2
	CURRENT_DATE=`date +%d`;
	FROM_DATE="$CURYR-$CURMTH-01"
	TO_DATE="$CURYR-$CURMTH-$CURRENT_DATE"
	# convert in seconds sinch the epoch:
	start=$(date -d$FROM_DATE +%s)
	end=$(date -d$TO_DATE +%s)
	cur=$start
	while [ $cur -le $end ]; do
	# convert seconds to date:
	REPORT_DATE=$REPORT_DATE$(date -d@$cur +%Y-%m-%d)",";
	let cur+=24*60*60
	done
	# Remove last comma (,)
	REPORT_DATE=${REPORT_DATE::-1}
	echo $REPORT_DATE;

view raw generate-dates-from-today-till-start-of-the-month.sh hosted with ❤ by GitHub