Re: script to loop through dates

[Will McDonald <wmcdonald@xxxxxxxxx>]

On Fri, 27 Jun 2025 at 12:32, olivares33561 via users <users@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

I am struggling to create a script that generates a series of dates with special "+%Y.%m.%d" like the following

2025.06.01
2025.06.01
2025.06.01

I found several examples but can't succeed to get what I want
------

#!/bin/bash
start=$1
end=$2

start=$(date -d $start +%Y%m%d)
end=$(date -d $end +%Y%m%d)

while [[ $start -le $end ]]
do
    echo $start
    start=$(date -d"$start + 1 day" +"%Y%m%d")
done
------

The date command can't parse dates with periods/dots in this step:  start=$(date -d $start +%Y%m%d)

Example:

wmcdonald@DESKTOP-9HGJE25:~$ echo $IN
2025.07.01
wmcdonald@DESKTOP-9HGJE25:~$ date -d $IN +%Y%m%d
date: invalid date ‘2025.07.01’
wmcdonald@DESKTOP-9HGJE25:~$

So that step's going to fail. And the while loop can't evaluate the dotted notation strings for greater/less than. The easiest thing to do is strip the dots from the input, then add them back in in the output. This isn't elegant, and someone may provide a better answer but this works:

#!/bin/bash
start=$1
end=$2

start=$(date -d $(echo $start | sed 's/\./-/g') +%Y%m%d)
end=$(date -d $(echo $end | sed 's/\./-/g') +%Y%m%d)

date -d"$start" +%Y.%m.%d

while [[ $start -lt $end ]]
do
    date -d"$start + 1 day" +%Y.%m.%d
    start=$(date -d"$start + 1 day" +%Y%m%d)
done

wmcdonald@DESKTOP-9HGJE25:~$ ./daterange.sh 2025.07.01 2025.07.16
2025.07.01
2025.07.02
2025.07.03
2025.07.04
2025.07.05
2025.07.06
2025.07.07
2025.07.08
2025.07.09
2025.07.10
2025.07.11
2025.07.12
2025.07.13
2025.07.14
2025.07.15
2025.07.16

 

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