CODEWITHSUNDEEP
bash
Vincenzo
Vincenzo

Reputation: 97

BASH: print the next monday of date

How can I calculate the date of the Monday of next week? For example, if I have one variable with this day:

DAYCHECK=2012-10-24

the calculation of the next-monday doesn't work:

date -d $DAYCHECK -dnext-monday +%Y%m%d

UPDATE:

I have solved whit this method:

numdaycheck=`date -d $DAYCHECK +%u`
sum=$((8-$numdaycheck))
date=`date -d "$DAYCHECK $sum days" +%Y%m%d`

Upvotes: 4

Views: 4533

Answers (3)

Nahuel Fouilleul
Nahuel Fouilleul

Reputation: 19315

next_monday() {
  local yi=${1:0:4} mi=${1:5:2} di=${1:8:2}
  mi=${mi#0}
  di=${di#0}
  local yo=$yi mo=$mi do
  do=$(cal -m $mi $yi|awk 'c==1{print$1;exit}NR>2&&/'"$di"'/{c++}')
  if [ "X$do" = X ];then
    ((mo=mi+1))
    if ((mo>12)); then
      ((mo=1,yo=yi+1))
    fi
    do=$(cal -m $mo $yo|awk 'NR>2&&!/^  /{print$1;exit}')
  fi
  printf "%04d-%02d-%02d\n" $yo $mo $do
}

Upvotes: 0

Kent
Kent

Reputation: 195049

(echo commands are not necessary.)

kent$  w=$(date -d2012-10-24 +%u) // here get the weekday index

kent$  echo $w
3

kent$  s=$(((7-$w+2)*3600*24+$(date -d2012-10-24 +%s))) //here get the "next monday" seconds

kent$  echo $s
1351548000

kent$   echo $(date +%Y-%m-%d -d "1970-01-01 UTC $s seconds") //finally we get the date of "next monday"
2012-10-29

so the "2012-10-29" is the final answer.

This way is not as simple as chepner's . I post as another answer because I usually do date calculation with it. for example add 5 hours 30 mins to a given date. just change (7-$w+2)*3600*24 part will do.

Hope it helps someone some day.

Upvotes: 0

chepner
chepner

Reputation: 531075

If GNU date (or any other date) accepts some variation of "monday after $DAYCHECK", I haven't seen it. I think you have to do the math.

$ day_of_week=$( date +%u --date $DAYCHECK)   # 1 = Monday, ... 7 = Sunday
$ date --date "$DAYCHECK +$((8-day_of_week)) days"

If DAYCHECK is already a Monday, you'll get the following Monday. If you want DAYCHECK instead, you'll need to handle it separately:

$ if (( day_of_week == 1 )); then
> date --date "$DAYCHECK"
> else
> date --date "$DAYCHECK +$((8-day_of_week)) days"
> fi

Upvotes: 5

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