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

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I need to remove files older than 3 days with a cron job in 3 different directories. (these 3 directories are children of a parent directory /a/b/c/1 & /a/b/c/2 & /a/b/c/3) Can this be done with one line in the crontab?

Best Answer

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.

Related Solutions

Shell – Delete files older than 500 days

You're missing that find doesn't need a list of files as input. The problem is that the glob /var/log/arc/* expands to too many files. However, find will recurse into subdirectories by default, so there's no need to use the glob at all:

find /var/log/arc/ -type f -mtime +500 -delete

-delete is a non-standard predicate. If your find implementation doesn't support it, you can use:

find /var/log/arc/ -type f -mtime +500 -exec rm -f {} +

instead.

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

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.