How to find the difference in days between two dates

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A  2002-20-10  B  2003-22-11    How to find the difference in days between two dates

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tl dr date diff        date -d  quot 2015-03-11 UTC quot    s  -   date -d  quot 2015-03-05 UTC quot    s      60 60 24      Watch out  Many of the bash solutions here are broken for date ranges which span the date when daylight savings time begins  where applicable   This is because the     math    construct does a  floor  truncation operation on the resulting value  returning only the whole number  Let me illustrate  DST started March 8th this year in the US  so let s use a date range spanning that  start ts   date -d  quot 2015-03-05 quot     s   end ts   date -d  quot 2015-03-11 quot     s    Let s see what we get with the double parentheses  echo       end ts - start ts    60 60 24      Returns  5   Doing this using  bc  with more accuracy gives us a different result  echo  quot scale 2     end ts -  start ts    60 60 24  quot    bc  Returns  5 95  - the missing 0 05 being the lost hour from the DST switchover  So how should this be done correctly  I would suggest using this instead  printf  quot   0f quot    echo  quot scale 2     end ts -  start ts    60 60 24  quot    bc   Here  the  printf  rounds the more accurate result calculated by  bc   giving us the correct date range of  6   Edit  highlighting the answer in a comment from  hank-schultz below  which I have been using lately  date diff        date -d  quot 2015-03-11 UTC quot    s  -   date -d  quot 2015-03-05 UTC quot    s     60 60 24      This should also be leap second safe as long as you always subtract the earlier date from the later one  since leap seconds will only ever add to the difference - truncation effectively rounds down to the correct result

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And in python   python -c  from datetime import date  print  date 2003 11 22 -date 2002 10 20   days  398

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This assumes that a month is 1 12 of a year      usr bin awk -f function mktm datespec      split datespec  q   -     return q 1    365 25   q 3    365 25   12   q 2    BEGIN     printf   d n   mktm ARGV 2   - mktm ARGV 1

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Instead of hard coding the expiration to a set amount of days when generating self-signed certificates  I wanted to have them expire just before the Y2k38 problem kicks in  on 19 January 2028   But  OpenSSL only allow the expiration to be set using -days  which is the number of days from the current date  I ended up using this  openssl req -newkey rsa -new -x509     -days         2  31   -   date   s   86400-1       -nodes -out new crt -keyout new key -subj   CN SAML SP

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Give this a try   perl -e  use Date  Calc qw Delta Days   printf   d n   Delta Days 2002 10 20 2003 11 22

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This works for me   A  2002-10-20  B  2003-11-22  echo        date -d  B   s  -   date -d  A   s     86400    days   Prints  398 days   What is happening    Provide valid time string in A and B  Use date -d to handle time strings Use date  s to convert time strings to seconds since 1970  unix epoche  Use bash parameter expansion to subtract seconds divide by seconds per day  86400 60 60 24  to get difference as days    DST is not taken into account   See this answer at unix stackexchange

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The bash way - convert the dates into  y m d format and then you can do this straight from the command line   echo        date --date  031122    s  -   date --date  021020    s     60 60 24

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If you have GNU date  it allows to print the representation of an arbitrary date  -d option   In this case convert the dates to seconds since EPOCH  subtract and divide by 24 3600   Or you need a portable way

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Use the shell functions from http   cfajohnson com shell ssr ssr-scripts tar gz  they work in any standard Unix shell   date1 2012-09-22 date2 2013-01-31   date-funcs-sh  date2julian   date1  jd1   DATE2JULIAN  date2julian   date2  echo      DATE2JULIAN - jd1      See the documentation at http   cfajohnson com shell ssr 08-The-Dating-Game shtml

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Here s the MAC OS X version for your convenience     A  2002-20-10   B  2003-22-11     echo      date -jf  Y- d- m  B   s  -  date -jf  Y- d- m  A   s   86400     nJoy

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echo   date   d  h  y  date today echo   The other date is 1970 01 01  TODAY DATE  1970-01-01  BEFORE DATE   date   d h y  echo  THE DIFFERNS IS          date -d  BEFORE DATE   s  -   date -d  TODAY DATE   s      SECOUND   use it to get your date today and your sec since the date you want  if you want it with days just divide it with 86400  echo   date   d  h  y  date today echo   The other date is 1970 01 01  TODAY DATE  1970-01-01  BEFORE DATE   date   d h y  echo  THE DIFFERNS IS          date -d  BEFORE DATE   s  -   date -d  TODAY DATE   s    86400   SECOUND

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on unix you should have GNU dates installed   you do not need to deviate from bash   here is the strung out solution considering days  just to show the steps   it can be simplified and extended to full dates    DATE   echo  date   DATENOW   echo  date -d   DATE    j   DATECOMING   echo  date -d  20131220    j   THEDAY   echo  expr  DATECOMING -  DATENOW    echo  THEDAY

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If the option -d works in your system  here s another way to do it  There is a caveat that it wouldn t account for leap years since I ve considered 365 days per year   date1yrs  date -d  20100209    Y  date1days  date -d  20100209    j  date2yrs  date   Y  date2days  date   j  diffyr  expr  date2yrs -  date1yrs  diffyr2days  expr  diffyr    365  diffdays  expr  date2days -  date1days  echo  expr  diffyr2days    diffdays

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Even if you don t have GNU date  you ll probably have Perl installed   use Time  Local  sub to epoch     my   t           my   y   d   m      t       d 4  -  d 2  -  d 2        return timelocal 0  0  0   d 0   m-1   y-1900     sub diff days     my   t1   t2           return  abs to epoch  t2  - to epoch  t1      86400    print diff days  2002-20-10    2003-22-11      n     This returns 398 041666666667 -- 398 days and one hour due to daylight savings     The question came back up on my feed  Here s a more concise method using a Perl bundled module  days   perl -MDateTime -le       sub parse date             f   split  -   shift          return DateTime- gt new year  gt  f 0   month  gt  f 2   day  gt  f 1               print parse date shift - gt delta days parse date shift  - gt in units  days       A  B  echo  days       gt  398

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This is the simplest i managed to get working on centos 7   OLDDATE  2018-12-31  TODAY   date -d   date   Y- m- d     s   LINUXDATE   date -d   OLDDATE     s   DIFFDAYS       TODAY -  LINUXDATE     60 60 24      echo  DIFFDAYS

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Using mysql command    echo  select datediff  2013-06-20 18 12 54 08 00    2013-05-30 18 12 54 08 00        mysql -N   Result  21  NOTE  Only the date parts of the values are used in the calculation  Reference  http   dev mysql com doc refman 5 6 en date-and-time-functions html function datediff

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Another Python version   python -c  from datetime import date  print date 2003  11  22  toordinal   - date 2002  10  20  toordinal

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Assume we rsync Oracle DB backups to a tertiary disk manually  Then we want to delete old backups on that disk  So here is a small bash script      bin sh  for backup dir in    backup cmsprd local backupset    backup cmsprd local autobackup    backup cfprd backupset    backup cfprd autobackup   do      for f in  find  backup dir -type d -regex            -printf   f n       do          f2  echo  f   sed -e  s    g           days      date    s   -  date -d    f2      s    86400            if    days -gt 30    then             rm -rf  backup dir  f         fi      done  done   Modify the dirs and retention period   30 days   to suit your needs

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For MacOS sierra  maybe from Mac OS X yosemate    To get epoch time Seconds from 1970  from a file  and save it to a var   old dt  date -j -r YOUR FILE    s     To get epoch time of current time  new dt  date -j    s     To calculate difference of above two epoch time     diff   new dt - old dt      To check if diff is more than 23 days     new dt - old dt  gt   23 86400      amp  amp  echo Is more than 23 days

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Here s my working approach using zsh  Tested on OSX     Calculation dates    A random old date START DATE  2015-11-15     Today s date TODAY   date   Y- m- d     Import zsh date mod zmodload zsh datetime    Calculate number of days DIFF         strftime -r  Y- m- d  TODAY  -   strftime -r  Y- m- d  START DATE      86400    echo  Your value     DIFF   Result   Your value   1577   Basically  we use strftime reverse  -r  feature to transform our date string back to a timestamp  then we make our calculation

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I d submit another possible solution in Ruby  Looks like it s the be smallest and cleanest looking one so far   A 2003-12-11 B 2002-10-10 DIFF   ruby -rdate -e  puts Date parse   A   - Date parse   B     echo  DIFF

[bash] How to find the difference in days between two dates?

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