We have this string to retrieve date and time in clean format.
TIMESTAMP=$(date "+%Y%m%d%H%M") Is there some inline code that we can use to round the minute to 5 down. So if it is 12:03 it will make it 12:00 and if it is 12:49 it will be 12:45
Thank you!
To do this you can subtract the minutes modulo 5 from the total minutes. To print it out:
echo "$(date "+%Y%m%d%H%M") - ($(date +%M)%5)" | bc To save it to a variable:
my_var=$(echo "$(date "+%Y%m%d%H%M") - ($(date +%M)%5)" | bc) This relies on your date format string remaining as it is now - a string of numbers.
Example output:
$ date "+%Y%m%d%H%M" 201404010701 $ echo "$(date "+%Y%m%d%H%M") - ($(date +%M)%5)" | bc 201404010700 
echo "$(TZ=UTC date "+%Y%m%d%H%M") - ($(date +%M)%5)" | bc
A little string manipulation:
case $TIMESTAMP in *[1234]) TIMESTAMP=${TIMESTAMP%?}0;; *[6789]) TIMESTAMP=${TIMESTAMP%?}5;; esac ${TIMESTAMP%?} removes the last character. Ref: http://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameter-Expansion
date only once.Not exactly bash only but using dateutils' dround utility, it boils down to:
$ dround now -5m 2014-04-01T10:35:00 or with your format specifiers:
$ dround now -5m -f '%Y%m%d%H%M' 201404011035 Disclaimer: I am the author of that project.
You can use the integer division and multiply back to get the round value.
$ m=23 $ (( m /= 5, m *= 5 )) && echo $m 20 Integer division just return the integer part of the result, so in the case above is returning 4. Then multiplying by 5 gives 20.
In your case:
$ TIMESTAMP=$(date "+%Y%m%d%H%M") $ echo $TIMESTAMP 201404011231 $ (( TIMESTAMP /= 5, TIMESTAMP *= 5 )) $ echo $TIMESTAMP 201404011230 $ TIMESTAMP=$(date "+%Y%m%d%H%M") $ echo $TIMESTAMP 201404011257 $ (( TIMESTAMP /= 5, TIMESTAMP *= 5 )) $ echo $TIMESTAMP 201404011255 (( ... )) expression, e.g. (( TIMESTAMP /= 5, TIMESTAMP *= 5 )).
using the remainder operator the we can determine the number of excess minutes, that can then be subtracted from the original:
TIMESTAMP=$(date "+%Y%m%d%H%M") (( TIMESTAMP -= TIMESTAMP%15 )) echo $TIMESTAMP this only works because both 100 and 60 are divisible by 5 if 15 minutes was wanted instead of 5 the expression would be more complex:
(( TIMESTAMP -= TIMESTAMP%100%5 )) The solution of Fedorqui is very smart and versatile:
seconds=$(date +%s) echo $seconds $(date --date="@$seconds" +%H:%M:%S) # say 1559449650 # 06:27:30 # (( seconds /= 3600, seconds *= 3600 )) # rounds to this hour # (( seconds += 3600, seconds /= 3600, seconds *= 3600 )) # rounds to next hour (( seconds += 1800, seconds /= 1800, seconds *= 1800 )) # rounds to next half of a hour next_hour=$(date --date="@$seconds" +%H:%M:%S) echo $seconds $next_hour # say 1559449800 06:30:00 With Bash:
Following one-liner rounds the minutes down to steps of 5 minutes:
d=$(date +'%M'); echo $(date +'%d/%m/%Y %H:')$((($(($d / 5))-0)*5))':'$(date +'%M') output example:
Sat Apr 24 12:16:00 CEST 2021 24/04/2021 12:15:16
echo $(date +'%Y-%m-%d %H:')$(( ($(date +'%M') / 5)*5 ))With bash:
TIMESTAMP=$(date "+%Y%m%d%H%M")
MINROUND=$((10#${TIMESTAMP:10:2} / 5 * 5)) if [ "${#MINROUND}" = 1 ]; then MINROUND="0$MINROUND" fi TIMESTAMP="${TIMESTAMP:0:10}${MINROUND}" 
TIMESTAMP=$(date "+%Y%m%d%H%M")