find -delete works OK, but not with cron

Question

PLEASE NOTE: I have read all the similar questions re. cron, paths, env variables and so on, but have found none that offer solutions to my particular problem.

---

I have a script that makes some MySQL dumps and then deletes old ones like this:

/usr/bin/find "/home/bkp/dbdump" -name "*.gz" -mtime +5 -delete

(above command has been modified from my original command by suggestions from comments)

However, the files are never deleted when cron runs this script. The cron user is root.

Debugging notes

• If I manually run the script in which the command appears, it deletes them as expected.

• If I run the above find command on its own from the command line as root, it deletes them as expected (and with -print it returns a list of files older than 5 days as expected)

• I have also added an explicit path statement to root's crontab, but
  that doesn't change anything.

• Cron sends no error, and if I pipe the find operation to a log file,
  that comes up empty or is not created at all.

• I'm using Ubuntu server 14.04.03 LTS.

Answer 1

The problem is that crontab doesn't have $PATH set when it runs. You can actually provide it with a path by adding this to the top of the file opened via crontab -e:

PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin

(or whatever PATH you'd prefer to use). This means you can avoid specifying the full paths to commands, directly from cron.

There are multiple problems with your original command. You're basically asking the shell to do the wildcard expansion, rather than find. Secondly, you're not providing a full path for rm; use /bin/rm or /usr/bin/rm, wherever it's located on your system (see which rm).

The first argument for find is the "location to search", and then you specify the "search query" with the various -<option>s. So, the proper format of the command you want to run is:

find "/home/bkp/dbdump" -name "*.gz" -mtime +5 -exec rm -f {} \;

or

find "/home/bkp/dbdump" -name "*.gz" -mtime +5 delete

If you don't specify the PATH definition like above, use:

/usr/bin/find "/home/bkp/dbdump" -name "*.gz" -mtime +5 -exec /bin/rm -f {} \;

or

/usr/bin/find "/home/bkp/dbdump" -name "*.gz" -mtime +5 delete

Answer 2

Try this instead

find /home/bkp/dbdump -type f -name '*.gz' -mtime +5 -delete

Answer 3

If I invoke the find command directly from root's crontab and not as part of the script, then it works.

The script in question uses csh. I believe that root's cron environment on Ubuntu will be using /bin/bash (or /bin/dash?). Perhaps this conflicts in some way with how the find command was running.

Either way, the main issue it solved, albeit somewhat inelegantly.

Answer 4

Dear Crontab uses sh shell instead of bash by default. you can use /dev/null to empty files. check below script. it will help.

#!/bin/bash
tar=$(ls -lt /backup/manual | grep ^d | tail -n1 | awk '{print $NF}')
for i in $(find /backup/manual/"$tar" -type f ) 
 do cat /dev/null > "$i" 
done > /dev/null 2>&1 && mv /backup/manual/"$tar" /tmp/

explanation: kindly use for loop to reach all files from targeted folders and make them null and move to /tmp directory at last