Find files older than a given file minus a few hours

Question

I'm using the following to find all files that are older than a reference file...

find /home/testuser -name "dummyfiles*" ! -newer referencefile.txt

... which works as expected.

However, I want to add a bit of leniency to the time, so that it only finds files that are older than the reference file - a few hours.

For example, if I have a reference file with modification date May 26 11:26, I want to find files that are older than May 26 9:26 (ie, with a 2-hour leniency on the reference file).

In this example, the following would be correct matches...

May 26 7:00
Apr 15 14:00

... and the following should not match...

Jun 13 9:00
May 26 10:00

Ultimately I want to delete all the files that I find, so would love it if find was able to handle this requirement? Otherwise, are there any other alternatives that will allow me to delete these files without being too convoluted?

Answer 1

On a GNU system, you could do something like:

TZ=UTC0 find /home/testuser -name "dummyfiles*" ! -newermt "$(
  TZ=XXX2:00:00 date -r referencefile.txt +%FT%T.%N)"

That is, get date to print the modification of the file in a timezone 2 hours behind UTC (so if the file was last modified at 15:00 UTC, date will print 13:00) and get find to interpret that timestamp as UTC time (so in our example, will try to find files last modified before 13:00 UTC).

That's limited to offsets of up to 24 hours (or 48 hours if you use TZ=XXX-24 for find). For arbitrary offsets, you can do:

(
export TZ=UTC0
find /home/testuser -name "dummyfiles*" ! -newermt "$(
  date -d "$(date -r referencefile.txt +%FT%T.%N) - 2 hours" +%FT%T.%N)"
)

Or you could use perl:

perl -MFile::Find -le '
  $min_age = (-M "referencefile.txt") + 2/24;
  find (sub {
    print $File::Find::name if $_ =~ /^dummyfiles/ && (-M$_) > $min_age
    }, @ARGV)
  ' -- /home/testuser

Note that contrary to find (but like GNU date -r), for symlinks perl's -M considers the age of the file it links to, not the age of the symlink itself. The subsecond part of the timestamp is also not considered.

Answer 2

Try out with this :

find /home/testuser -name "dummyfiles*" ! -newer referencefile.txt -mmin +120 -print

adding the parameter -mmin +120 find command will return only the files older than 2-hour in comparison to referencefile.txt modification date.

test:

mkdir find
touch find/dummyfiles1 find/dummyfiles2 find/dummyfiles3 find/dummyfiles4 find/referencefile.txt
touch -t 8001031305 dummyfiles1 dummyfiles2
find find/ -name "dummyfiles*" ! -newer find/referencefile.txt -mmin +120

output:

find/dummyfiles1

find/dummyfiles2