If you have a directory that you want to keep clean, tmpreaper is a great way to remove files based on how old they are. The other day, I had a directory that looked like this:

x@x:~/dump$ ls -l
-rw-r--r-- 1 x x 212268169 Mar 15 01:02 x-2015-03-15.sql.gz
-rw-r--r-- 1 x x 212270156 Mar 16 01:02 x-2015-03-16.sql.gz
-rw-r--r-- 1 x x 212276275 Mar 17 01:02 x-2015-03-17.sql.gz
-rw-r--r-- 1 x x 212308369 Mar 18 01:02 x-2015-03-18.sql.gz
-rw-r--r-- 1 x x 212315343 Mar 19 01:02 x-2015-03-19.sql.gz
-rw-r--r-- 1 x x 212324575 Mar 20 01:02 x-2015-03-20.sql.gz
-rw-r--r-- 1 x x 212341738 Mar 21 01:02 x-2015-03-21.sql.gz
-rw-r--r-- 1 x x 212375590 Mar 22 01:02 x-2015-03-22.sql.gz
-rw-r--r-- 1 x x 212392563 Mar 23 01:02 x-2015-03-23.sql.gz

I decided that I didn't need those SQL dumps older than 30 days, so I would use tmpreaper to clean them. The proper command is

tmpreaper +30d /home/x/dump

I added the --test flag just to make sure my command would work. But, alas! Nothing happened:

x@x:~/dump$ tmpreaper --test +30d /home/x/dump
(PID 4057) Pretending to clean up directory `/home/x/dump'.

That's when I realized that this is the directory that I had recently recompressed all the files using gzip -9 to get better compression. Although ls was reporting the time the original files were created, this is not the time tmpreaper was looking at. You can see what I mean if you use ls -lc:

x@x:~/dump$ ls -lc
total 7863644
-rw-r--r-- 1 x x 212268169 Apr 11 03:03 x-2015-03-15.sql.gz
-rw-r--r-- 1 x x 212270156 Apr 11 03:06 x-2015-03-16.sql.gz
-rw-r--r-- 1 x x 212276275 Apr 11 03:09 x-2015-03-17.sql.gz
-rw-r--r-- 1 x x 212308369 Apr 11 03:12 x-2015-03-18.sql.gz
-rw-r--r-- 1 x x 212315343 Apr 11 03:15 x-2015-03-19.sql.gz
-rw-r--r-- 1 x x 212324575 Apr 11 03:17 x-2015-03-20.sql.gz
-rw-r--r-- 1 x x 212341738 Apr 11 03:20 x-2015-03-21.sql.gz
-rw-r--r-- 1 x x 212375590 Apr 11 03:23 x-2015-03-22.sql.gz
-rw-r--r-- 1 x x 212392563 Apr 11 03:26 x-2015-03-23.sql.gz

In order to have tmpreaper look at the proper timestamp, use the --mtime flag:

x@x:~/dump$ tmpreaper --mtime --test +30d /home/x/dump
(PID 4362) Pretending to clean up directory `/home/x/dump'.
Pretending to remove file `/home/x/dump/x-2015-03-20.sql.gz'.
Pretending to remove file `/home/x/dump/x-2015-03-17.sql.gz'.
Pretending to remove file `/home/x/dump/x-2015-03-21.sql.gz'.
Pretending to remove file `/home/x/dump/x-2015-03-15.sql.gz'.
Pretending to remove file `/home/x/dump/x-2015-03-22.sql.gz'.
Pretending to remove file `/home/x/dump/x-2015-03-18.sql.gz'.
Pretending to remove file `/home/x/dump/x-2015-03-19.sql.gz'.
Pretending to remove file `/home/x/dump/x-2015-03-16.sql.gz'.