Linux – How to get relative date based on relative date by linux date command

datelinux

Can I get "last monday based on 10 minutes ago" by linux date command ?

For example

If you have faketime and your date is dynamically linked:

faketime -f -10m date -d 'last monday' '+%F %T'

With ksh93 (only builtin commands):

printf '%(%F %T)T\n' "$(printf '%(%Y.%m.%d)T' '10 minutes ago')-0 last monday"

Here, if it was last Sunday instead of last Monday, you could do:

date -d "$(date -d '10 minutes ago' +"%F -%u day")"

Or if it was last Saturday:

date -d "$(date -d '10 minutes ago' +"%F -%w day -1 day")"

But for last Monday or any other day of the week, it involves a bit of arithmetic:

eval "date -d \"$(date -d '10 minutes ago' +'%F -$(((%u+5)%%7+1)) day')\""

Otherwise, you can always do:

d=$(date -d 'last monday'); sleep 600; printf '%s\n' "$d"

;-)

Really ugly and probably works only with GNU date:

date -d "$( date -d "$( date +'%Y-01-01' ) +40 weeks") -$( date -d "$( date +'%Y-01-01' ) +40 weeks" +'%w' ) days+1 day" +'%Y-%m-%d'

Tested only for your 3 October example, may fail for some other cases.

Update: If you have a non eng locale you need to specify the output from the inner date to get to to work. (And %F just is YYYY-MM-DD).

date -d "$(date -d "$(date +'%Y-01-01') +40 weeks" +"%F") -$(date -d "$(date +'%Y-01-01') +40 weeks" +%w) days +1 day" +"%F"

With GNU date you can do it as simple as this:

date --date="3min"

But busybox seems not so smart (yet). The only reliable solution I came up with using bb is:

busybox date -D '%s' -d "$(( `busybox date +%s`+3*60 ))"

(you don't need the busybox parts if there is no other date implementation present)

If you want a formatted output, you could add this

busybox date -D '%s' +"%y%m%d%H%" -d "$(( `busybox date +%s`+3*60 ))"