15 min interval rounded parameter as starting and ending time in a specified format

Question

I wanted to pass parameters in a shell script which calls a java program...

For example the current time is 2011:02:23 01:05 then I need to floor to nearest whole time like 1:00 (starttime parameter to java program) if its 1:05 and 1:15 (end time parameter to java program) the below timestamps I wanted to dynamically pass to a java program based on current time.

Example param(15min interval) to pass to java program via shell script.

java 2011:02:23 01:00 (start time) 2011.02.23 01:15 (end time)
java 2011.02.23 01:15 (starttime) 2011.02.23 01:30 (end time)

Can I ? or is there any way to generate the date with time in above specified format in unix ?

Note : This date: get current 15 minute interval doesnt serve my purpose.

Answer 1

You can get the number of minutes multiple of 15 lower than current minutes (or minutes given in the first parameter) with:

a=$(date date -d "2011-02-23 01:05" +%-m)        # need only minutes.
a=${1:-"$a"}                   # or use the value from the first parameter.
a=${a#0}                       # remove one optional leading zero to
                               # avoid issues with 08 and 09.
b=$((a-a%15))                  # Round down to a 15 minutes multiple.
c=$((b+15))                    # end time

echo "$b $c"

If you need a full date string use:

$ printf 'java %s%02d\n' "$(date -d "2011-02-23 01:05" +"%Y:%m:%d %H:")" "$b"
java 2011:02:23 01:00

Or, in bash:

$ printf -v a '%(%s)T\n' -1
$ printf '%(java %Y-%m-%d %H:%M:%S)T\n' "$(( a - a % (60*15) ))"
java 2018-08-30 22:45:00