Bash – Delete Sub-Directories with YYYYMMDD in Name Older Than N Days

bashdirectoryfindrmtimestamps

I have a directory where daily subdirectories are created, literally named according to $date. How can I delete folders and their contents that are older than 7 days according to the YYYYMMDD in the file name and not the metadata date? Say I have (skipped some for brevity):

I would end up with the following folders (which those should keep):

20170828
20170901

I created a variable that holds the date 7 days ago:
dt_prev=$(date -d "`date`-7days" +%Y%m%d)

My thought was to ls -l a list of these folder names and compare row by row, but this involves cleaning that list, etc., and I figure there has to be an easier way.

Best Answer

I think the solution would be a simpler version of what glenn jackman posted, e.g.

seven_days=$(date -d "7 days ago" +%Y%m%d)
for f in [0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]; do
   [ -d "$f" ] || continue
   (( $f < $seven_days )) && echo rm -r "$f"
done

Remove the echo if the results look correct.

The -d test ensures that we only inspect (remove) directories.

Related Solutions

Linux – Cleaner Way to Delete Files with Datestamp in Name

Another way to delete all except the last 30 files:

rm $(ls -r | tail -n +31)

Or here is a shorter version of the script in the original post:

cd /opt/backup/mysql/dumps
d=$(date -r $(($(date +%s)-30*86400)) +%Y%m%d)
for f in all-mysql-*; do
    [[ ${f#all-mysql-} < $d ]] && rm $f
done

Shell Script – Cron Job to Delete Files Older Than 3 Days

This is easy enough (although note that this goes by a modification time more than 3 days ago since a creation time is only available on certain filesystems with special tools):

find /a/b/c/1 /a/b/c/2 -type f -mtime +3 #-delete

Remove the # before the -delete once you are sure that it is finding the files you want to remove.

To have it run by cron, I would probably just create an executable script (add a shebang - #!bin/sh to the top line of the file and make executable with chmod a+x), then put it in an appropriate cron directory like /etc/cron.daily or /etc/cron.weekly. Provided of course that you do not need a more specific schedule and that these directories exist on your distro.

Update

As noted below, the -delete option for find isn't very portable. A POSIX compatible approach would be:

find /a/b/c/1 /a/b/c/2 -type f -mtime +3 #-exec rm {} +

Again remove the # when you are sure you have the right files.

Update2

To quote from Stéphane Chazelas comment below:

Note that -exec rm {} + has race condition vulnerabilities which -delete (where available) doesn't have. So don't use it on directories that are writeable by others. Some finds also have a -execdir that mitigates against those vulnerabilities.