How to generate a year-quarter date from the command line?

One (kinda ugly) solution, using BASH arithmetic evaluation and the GNU date command:

echo $(date +%Y)q$(( ($(date +%-m)-1)/3+1 ))
echo $(date -d "-1 month" +%Y)q$(( ($(date -d "-1 month" +%-m)-1)/3+1 ))

Note that the %-m prevents date from 0-padding, so this will still work for August and September.

Use my dateutils:

dconv 2012-01-01 -f '%Y%Q'
=>
  2012Q1

The %q and %Q flags are specific to dateutils, and return the quarter as number or in the form Q<NUMBER>.

All solutions that divide by four fail, for instance November:

% echo $(( 11/4+1 ))
3

The correct math would be:

$(( (m-1)/3 +1 ))

And as such, the quarter of current and previous month would be:

echo curr ${y}q$(((m-1)/3+1))
if [ $m = 1 ]; then
  echo prev $((y-1))q4
else
  echo prev ${y}q$(((m-2)/3+1))
fi

It's only twelve values to check, really…

% for m in {1..12}; do echo $m Q$(((m-1)/3+1)); done
1 Q1
2 Q1
3 Q1
4 Q2
5 Q2
6 Q2
7 Q3
8 Q3
9 Q3
10 Q4
11 Q4
12 Q4

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