I was hoping to get some help with finding the difference in days between two dates.
Date 1: Sysdate
Date2: Mar 20 2022 (future)
What I was trying to do is convert it to EPOCH time, subtract and then divide by 86400 to get the number of days between the two dates. However, I've having issues with the systax. Here's what I've tried:
days_remaining=('date "+%s" -d "Mar 20 2022"'-'date "+%s" -d "$(date '+%b %d %Y')"')/86400
But the above isn't working. Any assistance would be appreciated.
To do calculations in bash you need an arithmetic context (( )). Also, to execute your date commands you have to put them inside $() instead of string quotes ''.
By the way: The last date command in date "+%s" -d "$(date '+%b %d %Y') isn't necessary. date -d 0:00 +%s will print the same unix time.
(( days_remaining = ($(date -d "Mar 20 2022" +%s) - $(date -d 0:00 +%s)) / 86400 ))
you can use this
days_remaining=$(($(($(date "+%s" -d "Mar 20 2022") - $(date "+%s" -d "$(date '+%b %d %Y')"))) / 86400))
I am trying to write a bash script, to merge 24 files in a given day. The requirement changes during Day light saving time changes, where I get 23 or 25 files.
So, with further research I realized that day-light savings begins on the second Sunday of March(23) of every year and ends on first sunday of Novemeber(25).
I need more inputs to get second sunday in a given month to do the check of finding 23 or 25 files for March and November respectively.
Any inputs to help me with this will be really appreciated.
Thank you
Here is the sample code to find 24 files in a day-
if [ -z "$1" ];then
now=$(date -d "-1 days" +%Y-%m-%d);
else now=$1;
fi
load_date='load_date='$now
singlePath="$newPath/$load_date"
fileCount=$(hdfs dfs -ls -R $hdfsPath/$load_date/ | grep -E '^-' | wc -l)
path=$hdfsPath/$load_date
if [ $fileCount -eq 24 ]; then
echo "All files are available for "$load_date;
hadoop fs -cat $path/* | hadoop fs -put - $singlePath/messages.txt
else echo $fileCount" files are available for "$load_date"! Please note, few files are being missed";
fi
I wouldn't hardcode the dates of DST transistions. I would just count "how many hours did today have":
a "normal" day:
$ diff=$(( $(date -d now +%s) - $(date -d yesterday +%s) ))
$ echo $(( diff / 3600 ))
24
"spring forward"
$ diff=$(( $(date -d "2019-03-10 23:59:59" +%s) - $(date -d "2019-03-09 23:59:59" +%s) ))
$ echo $(( diff / 3600 ))
23
"fall back"
$ diff=$(( $(date -d "2019-11-03 23:59:59" +%s) - $(date -d "2019-11-02 23:59:59" +%s) ))
$ echo $(( diff / 3600 ))
25
One thing to note: since bash only does integer arithmetic, if the difference is not 86400 but 86399, you get:
$ echo $((86399 / 3600))
23
So, better to query yesterday's time first in the tiny-but-non-zero chance that the seconds tick over between the 2 date calls:
diff=$(( -$(date -d yesterday +%s) + $(date -d now +%s) ))
Here, $diff will be 86400 or 86401 (for non DST transition days), and dividing by 3600 will give 24 not 23.
I have 2 dates that are both in ISO - 8061 compliant date format.
echo $START
2019-02-14T16:09:13Z
echo $END
2019-02-14T19:43:12Z
Now I want to find the time difference between both. I would prefer the difference to be in hours.
What Ive tried is :
echo "$(($(date -d "$START" '+%s') - $(date -d "$END" '+%s')))"
But it does not work. Any ideas whats the best way to solve this ?
I'd use the dateutils tools.
Then the answer becomes:
> datediff 2019-02-14T16:09:13Z 2019-02-14T19:43:12Z -f "%H hours"
3 hours
echo "$((($(date -d "$END" '+%s') - $(date -d "$START" '+%s'))/60/60))"
Output:
3
On macOS using the built-in BSD date a more verbose solution is required:
echo "$((($(date -jf '%Y-%m-%dT%H:%M:%SZ' "$END" '+%s') - \
$(date -jf '%Y-%m-%dT%H:%M:%SZ' "$START" +%s))/3600 ))"
Output:
3
Similar approach to #Cyrus's answer of converting to epoch first.
In short, I want something works like this:
When I input a date like 2012-12-27 and want to expand the date by
week(start with Monday), it
outputs:2012-12-24,2012-12-25,2012-12-26,2012-12-27,2012-12-28,2012-12-29,2012-12-30
When I input a date like 2012-12-27 and want to expand the date by month, it outputs:2012-12-01,2012-12-02 ... 2012-12-31
or, how can I group a bunch of dates by week? e.g. when I input2012-12-01,2012-12-02 ... 2012-12-31. It outputs:2012-12-01,2012-12-02|2012-12-03 ... 2012-12-09|2012-12-10 ... 2012-12-16|...|2012-12-31
I have no idea how to complete this, any clue may be helpful!
DAYSECS=86400 # seconds in a day
WEEKSECS=604800
echo "Expand on week:"
g_epoch=$(date +"%s" -d $1) # given date as seconds from epoch
g_dayno=$(date +"%u" -d $1) # given date as day of week
g_month=$(date +"%m" -d $1) # given month
g_year=$(date +"%Y" -d $1) # given year
s_epoch=$(($g_epoch - $DAYSECS * ($g_dayno - 1)))
e_epoch=$(($s_epoch + $WEEKSECS))
for etime in $(seq $s_epoch $DAYSECS $e_epoch); do
date +"%Y-%m-%d" -d "#$etime"
done
echo "Expand on month:"
s_epoch=$(date +"%s" -d "$g_year-$g_month-01")
e_epoch=$(($s_epoch + 4 * $WEEKSECS))
for etime in $(seq $s_epoch $DAYSECS $e_epoch); do
if [ $(date +"%m" -d "#$etime") -ne "$g_month" ]; then
break;
fi
date +"%Y-%m-%d" -d "#$etime"
done
The script below work out from #perreal, I leave it here because:
It shows the power of GNU date.
It makes #perreal 's idea more clear and more universal.
Thank you, perreal!
Here it is
dd="2012-12-27" # test date
DAYSECS=86400 # seconds in a day
echo "expand by week:"
s_epoch=$(date +%s -d "$dd -$(($(date +%u -d $dd) - 1)) day") # start date of the week
e_epoch=$(date +%s -d "1970-01-01 00:00:00 +0000 +${s_epoch} seconds +6 days") # end date of the week
for etime in $(seq $s_epoch $DAYSECS $e_epoch); do
date +"%Y-%m-%d" -d "#$etime";
done
echo "expand by month:"
s_epoch=$(date +%s -d "$dd -$(($(date +%d -d $dd) - 1)) day") # start date of the month
e_epoch=$(date +%s -d "1970-01-01 00:00:00 +0000 +${s_epoch} seconds +1 month -1 day") # end date of the month
for etime in $(seq $s_epoch $DAYSECS $e_epoch); do
date +"%Y-%m-%d" -d "#$etime";
done
How can I print the date which is a day before current time in Bash?
if you have GNU date and i understood you correctly
$ date +%Y:%m:%d -d "yesterday"
2009:11:09
or
$ date +%Y:%m:%d -d "1 day ago"
2009:11:09
If you have BSD (OSX) date you can do it like this:
date -j -v-1d
Wed Dec 14 15:34:14 CET 2011
Or if you want to do date calculations on an arbitrary date:
date -j -v-1d -f "%Y-%m-%d" "2011-09-01" "+%Y-%m-%d"
2011-08-31
date --date='-1 day'
MAC OSX
For yesterday's date:
date -v-1d +%F
where 1d defines current day minus 1 day. Similarly,
date -v-1w +%F - for previous week date
date -v-1m +%F - for previous month date
IF YOU HAVE GNU DATE,
date --date="1 day ago"
More info: https://www.cyberciti.biz/tips/linux-unix-get-yesterdays-tomorrows-date.html
Sorry not mentioning I on Solaris system.
As such, the -date switch is not available on Solaris bash.
I find out I can get the previous date with little trick on timezone.
DATE=`TZ=MYT+16 date +%Y-%m-%d_%r`
echo $DATE
Well this is a late answer,but this seems to work!!
YESTERDAY=`TZ=GMT+24 date +%d-%m-%Y`;
echo $YESTERDAY;
Advanced Bash-scripting Guide
date +%Y:%m:%d -d "yesterday"
For details about the date format see the man page for date
date --date='-1 day'
date -d "yesterday" '+%Y-%m-%d'
or
date=$(date -d "yesterday" '+%Y-%m-%d')
echo $date
Use Perl instead perhaps?
perl -e 'print scalar localtime( time - 86400 ) . "\n";'
Or, use nawk and (ab)use /usr/bin/adb:
nawk 'BEGIN{printf "0t%d=Y\n", srand()-86400}' | adb
Came across this too ... insane!
/usr/bin/truss /usr/bin/date 2>&1 | nawk -F= '/^time\(\)/ {gsub(/ /,"",$2);printf "0t%d=Y\n", $2-86400}' | adb
date --date='-1 day'
Not very sexy but might do the job:
perl -e 'my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time - 86400);$year += 1900; $mon+= 1; printf ("YESTERDAY: %04d%02d%02d \n", $year, $mon, $mday)'
Formated from "martin clayton" answer.
You could do a simple calculation, pimped with an regex, if the chosen date format is 'YYYYMM':
echo $(($(date +"%Y%m") - 1)) | sed -e 's/99$/12/'
In January of 2020 it will return 201912 ;-)
But, it's only a workaround, when date does not have calculation options and other dateinterpreter options (e.g. using perl) not available ;-)
short answer (GNU format):
date +%Y-%m-%d -d "-2 day"
if you are using OSX, but you need create for GNU compatible, install coreutils first
brew install coreutils
then edit your profile with:
#gnu coreutils first
export PATH="/usr/local/opt/coreutils/libexec/gnubin:$PATH"
re-start your terminal, and now you able to use GNU format!
yesterday=`date -d "-1 day" %F`
Puts yesterday's date in YYYY-MM-DD format into variable $yesterday.
#!/bin/bash
OFFSET=1;
eval `date "+day=%d; month=%m; year=%Y"`
# Subtract offset from day, if it goes below one use 'cal'
# to determine the number of days in the previous month.
day=`expr $day - $OFFSET`
if [ $day -le 0 ] ;then
month=`expr $month - 1`
if [ $month -eq 0 ] ;then
year=`expr $year - 1`
month=12
fi
set `cal $month $year`
xday=${$#}
day=`expr $xday + $day`
fi
echo $year-$month-$day
DST aware solution:
Manipulating the Timezone is possible for changing the clock some hours. Due to the daylight saving time, 24 hours ago can be today or the day before yesterday.
You are sure that yesterday is 20 or 30 hours ago. Which one? Well, the most recent one that is not today.
echo -e "$(TZ=GMT+30 date +%Y-%m-%d)\n$(TZ=GMT+20 date +%Y-%m-%d)" | grep -v $(date +%Y-%m-%d) | tail -1
The -e parameter used in the echo command is needed with bash, but will not work with ksh. In ksh you can use the same command without the -e flag.
When your script will be used in different environments, you can start the script with #!/bin/ksh or #!/bin/bash. You could also replace the \n by a newline:
echo "$(TZ=GMT+30 date +%Y-%m-%d)
$(TZ=GMT+20 date +%Y-%m-%d)" | grep -v $(date +%Y-%m-%d) | tail -1
Try the below code , which takes care of the DST part as well.
if [ $(date +%w) -eq $(date -u +%w) ]; then
tz=$(( 10#$gmthour - 10#$localhour ))
else
tz=$(( 24 - 10#$gmthour + 10#$localhour ))
fi
echo $tz
myTime=`TZ=GMT+$tz date +'%Y%m%d'`
Courtsey Ansgar Wiechers
date +%Y:%m:%d|awk -vFS=":" -vOFS=":" '{$3=$3-1;print}'
2009:11:9