Shell Programming and Scripting

Hi Folks,
I've put together a script for sorting my backup files into sub folders to be run from a cron job. Each file is named username.tar.gz and the file /etc/trueuserowners contains all users and their owner in the format "user: owner".
The script works fine identifying users and their owners and is as follows:

Code:

#!/bin/bash
_w="/path/to/backups"
_wb="$_w/*.tar.gz"

if [ -d "$_w" ]; then
        for f in $_wb
        do
                _f=$(basename $f)
                _user=${_f%%.*}
                _o=`grep "^$_user:" /etc/trueuserowners`
                _owner=${_o#* }
                if [ ! -d "$_w/$_owner" ]; then
                        `mkdir $_w/$_owner/`
                fi
                `mv $f $_w/$_owner/`
        done
fi

Say I have the following:

/path/to/backups/userabackup.tar.gz
usera is owned by resellera.

The first time the script runs, the script will create the following directory and move userabackup.tar.gz into it:

/path/to/backups/resellera

The script has an if in it to ensure that /path/to.backups/resellera is only created if it does not already exist as you can see. My problem is that the mv command appears to be backing up the directory and creating a new one instead of moving the file into the existing directory and replacing the file if it is already there.

For example:

The second time the script runs, /path/to/backups/resellera will be renamed to /path/to/backups/resellera.1 and a new /path/to/backups/resellera is created.
The third time, /path/to.backups/resellera.1 is renamed /path/to.backups/resellera.2, /path/to.backups/resellera to /path/to.backups/resellera.1 and a new directory created.

I shouldn't need to have the script remove the directory first and the mv command does not create backup directories like this when run from the console. The VERSION_CONTROL environment is not set.
Is there something specific that makes mv act like this when run from a cron job? Do I have to tell it to over-write instead of create these backups?

1) Lose the backticks. In this context they are neither necessary or desirable.
e.g. `mv $f $_w/$_owner/` becomes mv $f $_w/$_owner/

2) There is no code posted which mentions $VERSION_CONTROL

3) What is "act like this"? Please post detail of an example.

That seems to have done the trick, no more backed up directories. Cheers

It is an envirmont variable that can be set instead of the --backup option for mv. Documented in man mv, I only mentioned it so that noone suggested it as a possible explanation.

I already did, I was referring to mv "backing up" the current destination directory as dirname.1 instead of simply overwriting any files in the existing directory.

Actually I did make a slight mistake, the numbering of the backups starts at 0, not 1

Apparently this didn't fix it. For reference I have "alias mv='mv -i'" in my .bashrc so I've change the mv to mv -f and am hoping that'll sort it out tonight.

Apparantly I still don't have a fix for this..something like this should be nice and simple!

Please post the current version of the script and mention what Operating System and what Shell you have.

We would expect changes to these original lines because of out-of-context backticks:
There are ambiguty issues with $_w and $_wb . Try using "${_w}" and "${_wb}" .

Do any of your filenames or directory names contain space characters or characters special to Shell (e.g. colon)? If so, the "for" statement needs to be a "while" statement.

Btw. If there are no subdirectories under /path/to/backups the script can be much improved.

This is the full script. I have made an interesting observation however. I have a number of resellers with differename usernames. For some reason, the problem does not affect the folder for the reseller root. The folders don't have anything to do with usernames other than being named after a user - there's no permissions differences across any of the files yet for some reason the one called root somehow works.

Code:

#!/bin/bash
_d="/home/scadmin/cpbackup/daily"
_db="$_d/*.tar.gz"

for f in $_db
do
        _f=$(basename $f)
        _user=${_f%%.*}
        _o=`grep "^$_user:" /etc/trueuserowners`
        _owner=${_o#* }
        if [ ! -d "$_d/$_owner" ]; then
                mkdir $_d/$_owner/
        fi
        mv -f $f $_d/$_owner/
done

Code:

# uname -a
Linux fred.southportcomputers.co.uk 2.6.18-238.12.1.el5 #1 SMP Tue May 31 13:22:04 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux

Running Centos 5.6 x86_64.

The script runs from the root crontab and root's shell is /bin/bash.

There are no spaces or special characters in the path, only lowercase letters.

I'll try it with curly brackets as you suggest, the only bit I haven't got the curlys in it the for statement itself.

Code:

#!/bin/bash
_d="/home/backup/daily"
_db="$_d/*.tar.gz"

for f in $_db
do
        _f=$(basename $f)
        _user=${_f%%.*}
        _o=`grep "^$_user:" /etc/trueuserowners`
        _owner=${_o#* }
        if [ ! -d "${_d}/${_owner}" ]; then
                mkdir ${_d}/${_owner}/
        fi
        mv -f $f ${_d}/${_owner}/
done