List/remove files, with filenames containing string that's "more than a month ago"?

Question

I store some data in files which follow this naming convention:

/interesting/data/filename-YYYY-MM-DD-HH-MM

How do I look for the ones with date in file name < now - 1 month and delete them?

Files may have changed since they were created, so searching according to last modification date is not good.

What I'm doing now, is filter-ing them in python:

prefix = '/interesting/data/filename-'

import commands
names = commands.getoutput('ls {0}*'.format(prefix)).splitlines()

from datetime import datetime, timedelta

all_files = map(lambda name: {
    'name': name,
    'date': datetime.strptime(name, '{0}%Y-%m-%d-%H-%M'.format(prefix))
}, names)

month = datetime.now() - timedelta(days = 30)
to_delete = filter(lambda item: item['date'] < month, all_files)

import os
from operator import itemgetter
map(os.remove, map(itemgetter('name'), to_delete))

Is there a (oneliner) bash solution for this?

Answer 1

Can you use -ctime with find? For a file, ctime indicates the last time the file metadata has changed (file creation, rename, chmod, chown, chgrp, etc). For most logfiles, creation date and ctime would be the same.

Answer 2

Presuming GNU date and GNU find you can do it this way

#!/usr/bin/env bash

prefix="/interesting/data/filename-"
ref=/tmp/ref.$$
one_month_ago=/tmp/one_month_ago.$$
results=/tmp/results.$$

# create a file whose timestamp is "one month ago"
touch "$one_month_ago" -t $(date -d "-1 month" +%Y%m%d%I%M.%S)

while read -r file ; do
        # strip the prefix, leaving the suffix
        datestr=$(tail -c $(( ${#file} - ${#prefix} + 1 )) <<<"$file")

        # cut the date and time out of the suffix
        date=$(cut -d- -f1-3 <<<"$datestr")
        time=$(cut -d- -f 4- <<<"$datestr" | tr - :)

        # create a reference file whose timestamp matches the string from $file
        touch "$ref" -t $(date -d "$date $time" +%Y%m%d%I%M.%S)

        # ask find whether the reference file is not neewer (aka "is older") 
        # than one month ago
        find "$ref" -not -newer "$one_month_ago" > "$results" &&
                # results from find?
                [ -s "$results" ] &&
                # then rm the corresponding file
                echo rm -f -- "$file"

done < <(find -path "$prefix"'*')

# clean up
rm -f "$ref" "$one_month_ago" "$results"

But it's not exactly a oneliner.

Since this is under tested and somewhat dangerous I have included an echo prefix to the rm command, so you'll need to remove that once you verify that the results are correct.

One weakness here is in the initial selection of files. -path "$prefix"'*' presumes absolute paths and will break otherwise; a more intelligent selection is probably better, even if it's a simple shell glob (i.e., replace the while loop with for file in "$prefix*" ; do ... done. I didn't do this because I don't know whether or not such a glob expansion would overflow the maximum command length.