How to find files older than N days from a given timestamp - shell

Question

I want to find files older than N days from a given timestamp in format YYYYMMDDHH
I can find file older than 2 days with the below command, but this finds files with present time:
find /path/to/dir -mtime -2 -type f -ls
Lets say I give the input timestamp=2011093009 I want to find files older than 2 days from 2011093009.
Been doing my research, but can't seem to figure it out.

Answer 1

put one of the answers from here and using $() as suggested here
(updated as per comment by sputnick)
date=2011060109; find /home/kenjal/ -mtime $(( $(date +%Y%m%d%H) - $(date -d $date +%Y%m%d%H) ))

Answer 2

Basically this is accomplished by finding files in a range of dates...
I used perl to calculate the days from today to the given timestamp since GNU date is not available in my system, so -d is not an option. Code Below accepts date in format YYYYDDMM. See below:
#!/usr/bin/perl
use Time::Local;
my($day, $month, $year) = (localtime)[3,4,5];
$month = sprintf '%02d', $month+1;
$day = sprintf '%02d', $day;
my($currentYear, $currentDM) = ($year+1900, "$day$month");
my $todaysDate = "$currentYear$currentDM";
#print $todaysDate;
sub to_epoch {
my ($t) = #_;
my ($y, $d, $m) = ($t =~ /(\d{4})(\d{2})(\d{2})/);
return timelocal(0, 0, 0, $d+0, $m-1, $y-1900);
}
sub diff_days {
my ($t1, $t2) = #_;
return (abs(to_epoch($t2) - to_epoch($t1))) / 86400;
}
print diff_days($todaysDate, $ARGV[0]);
**Note: I'm no expert in Perl and this is the very first piece of code I modify/write. Having said that, I'm sure there are better ways to accomplish the above in Perl
Then the below korn script to perform what I needed.
#!/bin/ksh
daysFromToday=$(dateCalc.pl 20110111)
let daysOld=$daysFromToday+31
echo $daysFromToday "\t" $daysOld
find /path/to/dir/ -mtime +$daysFromToday -mtime -$daysOld -type f -ls
I'm finding all files older than +$daysFromToday, then narrowing the search to days newer than -$daysOld

Answer 3

#!/usr/bin/env bash
# getFiles arrayName olderDate newerDate [ pathName ]
getFiles() {
local i
while IFS= read -rd '' "$1"'[(_=$(read -rd "" x; echo "${x:-0}")) < $2 && _ > $3 ? ++i : 0]'; do
:
done < <(find "${4:-.}" -type f -printf '%p\0%Ts\0')
}
# main date1 date2 [ pathName ]
main() {
local -a dates files
local x
for x in "${#:1:2}"; do
dates+=( "$(date -d "$x" +%s)" ) || return 1
done
_=$dates let 'dates[1] > dates && (dates=dates[1], dates[1]=_)'
getFiles files "${dates[#]}" "$3"
declare -p files
}
main "$#"
# vim: set fenc=utf-8 ff=unix ts=4 sts=4 sw=4 ft=sh nowrap et:
This Bash script takes two dates and a pathname for find. getFiles takes an array name and the files with mtimes between the two dates are assigned to that array. This example script simply prints the array.
Requires a recent Bash, and GNU date. If it really has to be "N days", or you don't have GNU date, then there is no possible solution. You'll need to use a different language. No shell can do that using standard utilities.
Technically, you can calculate an offset in days using printf '%(%s)T' ... and some arithmetic, but there is no possible way to get the base date from a timestamp without GNU date, so I'm afraid you're out of luck.
Edit
I see this question has a ksh tag, in which case I lied, apparently ksh93's printf accepts a GNU date -d like string. I have no idea whether it's portable, and of course requires a system with ksh93 installed. You could do it in that case with some modification to the above script.