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I have the following in a shell script. How can I subtract one hour while retaining the formatting?
DATE=`date "+%m/%d/%Y -%H:%M:%S"`
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1 Answer. You can use date to convert to timestamp which is seconds, subtract the seconds and then convert back to HH:MM:SS .
Set it to the number of days that you want to subtract. Very slight improvement to the command - date --date="${dataset_date} -${date_diff} day" +%Y-%m-%d.
Sample shell script to display the current date and time #!/bin/bash now="$(date)" printf "Current date and time %s\n" "$now" now="$(date +'%d/%m/%Y')" printf "Current date in dd/mm/yyyy format %s\n" "$now" echo "Starting backup at $now, please wait..." # command to backup scripts goes here # ...
date command is used to display the system date and time. date command is also used to set date and time of the system. By default the date command displays the date in the time zone on which unix/linux operating system is configured. You must be the super-user (root) to change the date and time.
The following command works on recent versions of GNU date:
date -d '1 hour ago' "+%m/%d/%Y -%H:%M:%S"
date -v-60M "+%m/%d/%Y -%H:%M:%S"
DATE=`date -v-60M "+%m/%d/%Y -%H:%M:%S"`
If you have bash version 4.4+ you can use bash's internal date printing and arithmetics:
printf "current date: %(%m/%d/%Y -%H:%M:%S)T\n"
printf "date - 60min: %(%m/%d/%Y -%H:%M:%S)T\n" $(( $(printf "%(%s)T") - 60 * 60 ))
The $(printf "%(%s)T") prints the epoch seconds, the $(( epoch - 60*60 )) is bash-aritmetics - subtracting 1hour in seconds. Prints:
current date: 04/20/2017 -18:14:31
date - 60min: 04/20/2017 -17:14:31
if you need substract with timestamp :
timestamp=$(date +%s -d '1 hour ago');
This work on my Ubuntu 16.04 date:
date --date="@$(($(date +%s) - 3600))" "+%m/%d/%Y -%H:%M:%S"
And the date version is date (GNU coreutils) 8.25
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$ date +%Y-%m-%d-%H
2019-04-09-20
$ date -v-1H +%Y-%m-%d-%H
2019-04-09-19
But in shell use as like date +%Y-%m-%d-%H, date -v-1H +%Y-%m-%d-%H
45
Convert to timestamp (a long integer), subtract the right number of milliseconds, reformat to the format you need.
Hard to give more details since you don't specify a programming language...
37
If you need change timezone before subtraction with new format too:
$(TZ=US/Eastern date -d '1 hour ago' '+%Y-%m-%d %H:%M')
Here another way to subtract 1 hour.
yesterdayDate=`date -d '2018-11-24 00:09 -1 hour' +'%Y-%m-%d %H:%M'`
echo $yesterdayDate
Output:
2018-11-23 23:09
I hope that it can help someone.
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