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Write script to backup files and delete old backups:

#!/bin/sh

BACKUPDIR=/var/backups/files
ROTATE=1

mkdir -p $BACKUPDIR

CURRENT="$BACKUPDIR/`date +%Y-%m-%d`-files.tar.gz"

cd /var/ && tar czf $CURRENT www

find $BACKUPDIR -type f -mtime $ROTATE -exec rm {} \;

chmod 0600 $BACKUPDIR/*

Command Line (for testing):

find $BACKUPDIR -type f -mtime $ROTATE -exec rm {} \;

Somehow, the script does not work. However, if I execute it in the console, all is OK and old files get deleted. But if I run the script, files are not deleted (tar archive get created when I run the script). Why?

Script permissions are 755.

3
  • 1
    If you want to delete files more than 24hrs old, you should specify -mtime +0 for find. -mtime 1 means files 24hrs to 48hrs old.
    – yaegashi
    Jul 27, 2015 at 6:30
  • 4
    -mtime 1 mean exactly 1 day old from now, so may be there are not such files in your $BACKUPDIR
    – Costas
    Jul 27, 2015 at 7:51
  • 2
    rather than -exec rm {}, you might want to use the -delete option.
    – FelixJN
    Jul 27, 2015 at 8:39

1 Answer 1

1

As suggested by Fiximan, you probably want to use the -delete option, although that should make no difference in your situation, if you were to hit a filename with spaces or other special characters, your script would fail.

#!/bin/sh -e

BACKUPDIR=/var/backups/files

# I suggest a little more than 1 day (i.e. about 1 week of backups is
# probably safer.)
ROTATE=7

mkdir -p $BACKUPDIR

CURRENT="$BACKUPDIR/`date +%Y-%m-%d`-files.tar.gz"

# Create protected file, then backup data in it
touch $CURRENT
chmod 600 $CURRENT
cd /var/ && tar czf $CURRENT www

# Here we have the attempt at deleting, notice the "+"
find $BACKUPDIR -type f -name '*-files.tar.gz' -mtime +$ROTATE -delete

A few things:

  1. ROTATE=1 does not seem to make much sense, you probably want more than 1 backup, just in case. You often notice something's wrong a few days in... good luck if you have a backup from last night only!

  2. chmod 600 $CURRENT should be done as soon as possible; if you are really afraid for the security of the file, do it before creating the tarball (as shown in my sample.)

  3. Fix the find by adding a + in front of the $ROTATE number. This is something that gets me each time, so don't feel bad. Actually, if you use + it has the mean of older or equal, and if you use '-', the test is inverted (so -mtime +7 is more or less equivalent to ! -mtime -7 — probably within 1 day in between which is not unlikely to match one side or the other.) With a plain number as you used (-mtime 1), it will delete files that were modified on that particular day. If that script does not run for 3 days, then those 3 files won't ever get deleted.

  4. It is easier to use the -delete so you do not have to think about the quotations you missed in your sample code (i.e. -exec rm "{}" \;) in case the filename includes special characters.

  5. I suggest you add a -name because you have a simple way to know whether the file in question is a backup. This is just for security. If you never ever put any other file in that directory (like a copy of a backup you want to keep for a longer period of time) then you do not need it.

  6. Adding the -e option in the hash bang (#!/bin/sh -e) is a good idea so the script stops on the very first error. At times scripts run, generate errors, and you never see them.

1
  • FYI, -exec rm {} \; is perfectly safe as far as whitespace and special characters go. It won't delete directories, but that's not called for in this case.
    – Wildcard
    Jul 30, 2019 at 22:57

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