[yesterday date in shell/unix]

Solved
jebok Posted messages 371 Registration date   Status Member -  
 alibat -
Bonjour,

Which command (in shell-UNIX) displays yesterday's date?
PS: I clarify that it is for a ksh script

--
Thank you for your help

12 answers

  1. jipicy Posted messages 40842 Registration date   Status Moderator Last intervention   4 898
     
    Ben if it works, the proof is:
    In bash [jp@Mandrake jp]$ date --date '1 days ago' Tue Aug 2 11:38:36 CEST 2005 We switch shell (the command is an alias) [jp@Mandrake jp]$ kosh $ date --date '2 days ago' Mon Aug 1 11:39:00 CEST 2005 $ date --date '1 days ago' Tue Aug 2 11:39:22 CEST 2005 
    ;-))
    --
    Z'@+...che.
    JP : Zen, my Nuggets ! ;-) Knowledge is only good if it's shared. 
    15
  2. raidcha
     
    Under Solaris and HP-UX, there is a simpler solution than creating a script.
    Just play with the time zone (system variable $TZ).

    Example:
    # echo `TZ=MET+24 date +"%D"`
    gives: 11/28/05 (today is 11/29/05)

    The “+24” corresponds to the number of hours to "subtract" (+) from the current time; if you want to add them, use - (see below)
    %D corresponds to the date formatting (see man date): mm/dd/yy

    Similarly, you could get the date for tomorrow in the format yyyymmdd, for example….
    #echo `TZ=MET-24 date +"%Y%m%d"`
    gives: 20051128

    ... or the day after tomorrow (only works under Solaris):
    #echo `TZ=MET-48 date +"%Y%m%d"`
    this last command doesn’t work under HP-UX because it seems you can't go around the earth more than once with HP :p
    14
    1. Lucien Hercaud
       
      On Solaris, it works for a maximum of a few days' difference.
      For more than that, you need to compile a file with "zic", e.g.:

      -bash-3.00$ cat Delta
      # Example: 100 days in the future 100*24 hours
      Zone POSE/Zulu+2400 2400 - POSE
      # Example: 365 days in the past 365*24 hours
      Zone POSE/Zulu-8760 -8760 - POSE
      # Example: 1 year and 3 months in the past: (365+90)*24 hours
      Zone POSE/Zulu-10920 -10920 - POSE
      # Example: 2 years and 3 months in the past: (2*365+90)*24 hours
      Zone POSE/Zulu-19680 -19680 - POSE
      # Example: 5 years and 3 months in the past: (5*365+90)*24 hours
      Zone POSE/Zulu-46008 -46008 - POSE

      -bash-3.00$ /usr/sbin/zic Delta
      -bash-3.00$ TZ=POSE/Zulu+2400 date
      Thu Jan 19 12:36:59 POSE 2012
      -bash-3.00$ TZ=POSE/Zulu-46008
      -bash-3.00$ date
      Wed Jul 12 12:32:20 POSE 2006
      0
    2. ZdraL
       
      Great, it works thank you so much =)
      0
  3. sclamagirand Posted messages 1 Status Member 5
     
    Here is a script that should work:

    #!/bin/ksh
    #
    set -A DAYS Sat Sun Mon Tue Wed Thu Fri Sat
    set -A MONTHS Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    #
    # works on Linux
    #
    # date -d '1 days ago'
    #
    YESTERDAY=$((`date +%d` -1))
    MONTH=`date +%m`
    YEAR=`date +%Y`
    NDAY=`date +%u`
    WEEKDAY=${DAYS[`date +%u`]}
    #
    if [ $YESTERDAY -eq "0" ];
    then
    #
    MONTH=$((MONTH-1))
    #
    if [ $MONTH -eq "0" ];
    then
    #
    MONTH=12
    YEAR=$((YEAR-1))
    #
    fi
    #
    set `cal $MONTH ${YEAR}`
    shift $(($# - 1))
    YESTERDAY=$1
    #
    fi
    #
    TMONTH=${MONTHS[MONTH]}
    YEAR2=${YEAR##20}
    #
    # uncomment next line for debugging
    #
    echo ${WEEKDAY} ${YESTERDAY} ${TMONTH} ${YEAR}
    #
    echo ${YESTERDAY}${MONTH}${YEAR2}
    #
    5
    1. skea
       
      Thank you slamagirand, it's perfect!!!
      0
  4. jipicy Posted messages 40842 Registration date   Status Moderator Last intervention   4 898
     
    See there: http://www.commentcamarche.net/forum/affich-1712417#1
    Catch you later...che.
    JP: Zen, my Nuggets! ;-) Knowledge is only good if it is shared.
    1
    1. jebok Posted messages 371 Registration date   Status Member 51
       
      No, it doesn't work...

      --
      Thank you for your help.
      0
  5. francis
     
    if [ `expr `date +%d` - 1` -le 0 ]; then cal | grep -E "28|29|30|31" | awk ........... fi 


    anyway, I'm going to write it anyway...
    1
  6. [Dal] Posted messages 6122 Registration date   Status Contributor Last intervention   1 108
     
    Hello,

    You can also convert the current date to seconds since Epoch, then subtract 86400 (24*60*60) from the result and reconvert the obtained number to the desired date format.

    See man date, and man strftime for the formats.

    Dal
    1
  7. lionel sévérian
     
    Here is the solution to your problem. It works and it's ksh AIX...

    GetDate()
    { # GetDate nDays [format]
    # Example of usage: export NAMEDIR=$(GetDate -1 '+%Y.%m.%d')

    typeset -i nDays=$1; format=$2
    eval $(echo $TZ | sed '
    s!\([^-0-9]*\)\([-0-9]*\)\(.*\)!typeset -i localOffset=\2;zon1=\1;zon2=\3!')
    TZ=$zon1$((localOffset-24*nDays))$zon2 date $format

    }


    To be used in KSH function without moderation...
    Copy/Paste everything that is in bold...
    1
    1. Vag
       
      Thank you for this code, it really helped me out!! (and thanks Google)

      My problem was slightly different, I wanted to find the date of the last Sunday...

      Thanks to your script I was able to do this:

      case $(date +%a) in
      Mon ) diff=-1;;
      Tue ) diff=-2;;
      Wed ) diff=-3;;
      Thu ) diff=-4;;
      Fri ) diff=-5;;
      Sat ) diff=-6;;
      Sun ) diff=0;;
      esac
      DATE1=$(GetDate $diff '+%d/%m/%Y')

      It works but it's not very pretty :)

      Would it be possible to make a function GetDate2? with $1 = the day to get (for last Sunday we put Sun) and $2 still the format

      I'm sure it could be done recursively too :)
      0
  8. francois
     
    the syntax date X days ago does not exist on all Linux systems, not at all on proprietary Unix systems and not on all BSD systems either!

    to be banned forever as a consequence.
    one of the simple solutions:
    expr `date +%d` - 1


    and of course if we want to manage the month and the year we need to create a shell script
    that checks if the day is 0 then run cal of the previous month to see if it ends with 28, 29, 30, 31 and if it’s January subtract 1 from the year

    nothing simpler really
    0
    1. alibat
       
      Great! You're saving our lives!
      0
  9. tontonserver
     
    To calculate the date for J-1, don't overthink it:
    DATE=$((`/bin/date +'%Y%m%d'` - 1))
    There you go, it's in YYYYMMDD format, then, do it your way!
    @+
    0
    1. Goldmund
       
      It doesn't work on the 1st of the month!!
      0
  10. uu
     
    ```bash #!/bin/ksh
    #
    set -A DAYS Sat Sun Mon Tue Wed Thu Fri Sat
    set -A MONTHS Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
    set -A MONTH_ 12 01 02 03 04 05 06 07 08 09 10 11 12
    set -A DAYS_ 09 01 02 03 04 05 06 07 08 09
    #
    # works on Linux
    #
    # date -d '1 days ago'
    #
    #YESTERDAY=$((`date +%d` -1))
    date1=20070101
    YESTERDAY=$((`date -d $date1 +%d` -1))
    MONTH=`date -d $date1 '+%m' `
    YEAR=`date -d $date1 '+%Y' `
    NDAY=`date -d $date1 '+%d' `

    WEEKDAY=${DAYS[`date +%u`]}
    #
    if [ $YESTERDAY -eq "0" ];
    then
    #
    MONTH=$((MONTH-1))
    #
    if [ $MONTH -eq "0" ];
    then
    #
    MONTH=12
    YEAR=$((YEAR-1))
    #
    fi
    #
    set `cal $MONTH ${YEAR}`
    shift $(($# - 1))
    YESTERDAY=$1
    #
    fi
    #
    YESTERDAY_=$YESTERDAY
    if [ $YESTERDAY -ne "0" ];
    then
    if [ $YESTERDAY -le 9 ];
    then
    #
    YESTERDAY_=${DAYS_[YESTERDAY]}
    #
    fi
    fi
    #
    TMONTH=${MONTHS[MONTH]}
    T_MONTH=${MONTH_[MONTH]}
    YEAR2=${YEAR##20}
    #
    # uncomment next line for debugging
    #
    echo ${WEEKDAY} ${YESTERDAY} ${TMONTH} ${YEAR}
    #
    #echo ${YESTERDAY}${MONTH}${YEAR2}
    #
    date=${YEAR}${T_MONTH}${YESTERDAY_}
    echo $date
    # ```
    0
  11. ddark2002
     
    Hello,

    date=$(date)
    set $date

    date=$(date --date '1 days ago')
    set $datedate=$(date)
    set $date

    I would like to create a file with 2 time variables to make a comparison.
    diff -c /home/file_.$2$3 /home/file_.$2$3-1j > /home/test.log
    0
    1. dallas
       

      DTE=`date --date '24 hours ago' '+%Y%m%d'`
      0
    2. BBH
       
      ```html Use the following functions:

      function TimeToSecond {
      # ${1} = Optional date and time (YYYYMMDDHHMMSS); it defaults to current time
      ( typeset -r awk_date="\"y=\" substr(\$1,01,4) \"\\nm=\" substr(\$1,05,2) \"\\nd=\" substr(\$1,07,2)"
      typeset -r awk_time="\"h=\" substr(\$1,09,2) \"\\ni=\" substr(\$1,11,2) \"\\ns=\" substr(\$1,13,2)"
      if [ -z "${1}" ]
      then date +%Y%m%d%H%M%S
      else echo "${1}"
      fi |\
      awk "{ print ${awk_date} \"\\n\" ${awk_time} }"
      echo
      echo "m += 9"
      echo "if (m <= 11) {"
      print "\ty -= 1 }"
      echo "if (m > 11) {"
      print "\tm -= 12 }"
      print "(((((y-1)*1461+1)/4 - y/100 + y/400 + (m*153+2)/5 + d + 59)*24 + h)*60 + i)*60 + s")\
      | bc
      }

      function SecondsToTime {
      # ${1} = number of seconds since January 1st of year 0001
      ( echo "s = ${1}"
      echo "i = s/60"
      echo "s -= i*60"
      echo "h = i/60"
      echo "i -= h*60"
      echo "d = h/24"
      echo "h -= d*24"
      echo "d += 305"
      echo "b = d/146097"
      echo "d -= b*146097"
      echo "y = b*400"
      echo "b = d/36524"
      echo "if (b > 3) {"
      print "\tb = 3 }"
      echo "d -= b*36524"
      echo "y += b*100"
      echo "b = d/1461"
      echo "d -= b*1461"
      echo "y += b*4"
      echo "b = d/365"
      echo "if (b > 3) {"
      print "\tb = 3 }"
      echo "d -= b*365"
      echo "y += b"
      echo "m = (d*5+2)/153"
      echo "d -= (m*153+2)/5-1"
      echo "m += 3"
      echo "if (m > 12) {"
      print "\tm -= 12"
      print "\ty += 1 }"
      echo "y"
      echo "m"
      echo "d"
      echo "h"
      echo "i"
      echo "s"
      )\
      | bc | paste -s - | awk '{ printf "%04d%02d%02d%02d%02d%02d\n",$1,$2,$3,$4,$5,$6 }'
      } ```
      0