Hello,
I have a script that makes copies of specific folders. The script is executed once a day creating a folder with the current date (dd.mm.yyyy). The next day the situation is similar, but of course a folder with the next date is created. On the third day, the oldest directory is deleted and the next one is created.
Everything works well during the month. When there is a change of month, the script often ignores the older directories and does not delete them. Is it possible to correct this, where is the error? Here is the script:

#!/bin/bash
katalog1="/home/a/"
katalog2="/home/b/"
katalog3="/home/c/"
katalog4="/home/d/"
katalog5="/home/e/"
katalog6="/home/f/"
katalog7="/home/g/"
katalog8="/home/h/"

sciezka="/home/elicki"
current_date=$(date +"%d.%m.%Y")
backup_dir="/home/alamakota/$current_date"
data_minus_jeden=$(date -d "1 days ago" +"%d.%m.%Y")

for katalog in "$sciezka"/*; do
if [ -d "$katalog" ]; then
nazwa_katalogu=$(basename "$katalog")

if [[ $nazwa_katalogu < $data_minus_jeden ]]; then
rm -r "$katalog"
fi
fi
done
sleep 420
mkdir -p "$backup_dir"
cp $katalog1 $katalog2 $katalog3 $katalog5 $katalog6 $katalog7 $katalog8 -r "$backup_dir"/
chmod -R 755 $sciezka

thank you

Can you please edit the above to wrap the script in [code] [/code] tags? That would preserve the indentation and make it easier to interpret.

The comparison is comparing the dd.mm.yyyy and not a more parsable yyyy.mm.dd or the epoch.

To elaborate your if statement is using string comparison and not numbers which is why it fails at a new month. By changing the order of year in the file name string comparison will now be correct. The other method would be to convert the file name to its epoch value which is the number of seconds and then compare the numbers.

thank you for the explanation

You can do the alphabetic comparison if your filenames are in the big-medium-small order: "%Y-%m-%d"
GNU date has even a shortcut for it: date "+%F"

You create backup directories in /home/alamakota/
but you delete old ones in /home/elicki/ ??

Perhaps you can use an array: