Question

I would like to write a bash script that prints out the date in the following format:

20120205_16
(year)(month)(day)_(24 hour)

so the command to do this for the current date is:

date +'20%y%m%d_%H'

What i would like to do is print every date like this (using a for loop or something) from a specified date to another. For example:

20120205_16 -> 20120305_18 would be:

20120205_16
20120205_17
20120205_18
...
20120305_17
20120305_18

Obviously the two hard bits here are specifying the date and incrementing by hour.

Is it possible to do this easily with date or another method?

Answer 1

First, you get time_t values using the %s format:

start=$(date --date '5 feb 2012 16:00' +%s)
stop=$(date --date '5 mar 2012 18:00' +%s)

These are expressed in seconds. You can use a for loop on their values, increasing them by 1 hour (3600 seconds):

for t in $(seq ${start} 3600 ${stop})
do
    date --date @${t} +'%Y%m%d_%H'
done

Note the @ which is used to express times obtained through %+s in the --date argument.