custom backup

lionslair · 04-07-2006, 06:11 AM

I have written this bash script which runs every night to do a full backup of my system

Code:

#!/bin/sh
## BACKUP RZEPECKI-04 SYSTEM ##
## THIS SCRIPT PERFORMS A BACKUP OF THE LISTED DIRECTORIES TOO THE EXTERNAL USB HARD DRIVE
## PROCESS IS
## MOUNT THE EXTERNAL DRIVE (USB AT THE MOMENT)
## DO THE COPY OF THE DIRECTORIES
## UNMOUNT THE DRIVE

## MOUNT THE DRIVE
mount -t ext3 /dev/sda1 /mnt/backup
sleep 5

flag=$(cat /mnt/backup/flag)

echo $flag
echo

#do an if
if [ "$flag" = "A" ]; then
 flag=B
 echo THIS BACKUP WILL BE $flag
 echo
else
#if [ "$flag" = "B" ]; then
flag=A
echo THIS BACKUP WILL BE AN $flag
echo
fi



## below list the directories to backup
echo "BACKUP /home/* TO THE EXTERNAL BACKUP"
echo

#mkdir /mnt/backup/home
#cp -auv /home/* /mnt/backup/home/
#tar -mvx /home /mnt/backup
tar -czvf /mnt/backup/home-$flag.tgz /home
#rsync -a -delete /home/* /mnt/backup/home-$flag/

echo "FOLDERS: /home   BACKED UP"
echo "###############################################"
echo

## NEXT DIR ##

echo "BACKUP /etc/*"
echo

#mkdir /mnt/backup/etc
#cp -auv /etc/* /mnt/backup/etc/
tar -czvf /mnt/backup/etc-$flag.tgz /etc
#rsync -a -delete /etc/* /mnt/backup/etc-$flag

echo "FOLDERS /etc   BACKED UP"
echo "###############################################"
echo


## NEXT DIR ##

echo "BACKUP /usr/local/cvsroot/*"
echo

#mkdir /mnt/backup/usr/local/cvsroot
#cp -auv /usr/local/cvsroot/* /mnt/backup/usr/local/cvsroot/
tar -czvf /mnt/backup/cvsroot-$flag.tgz /usr/local/cvsroot
#rsync -a -delete /usr/local/cvsroot/* /mnt/backup/cvsroot-$flag

echo "FOLDERS /usr/local/cvsroot     BACKED UP"
echo "###############################################"
echo

## NEXT DIR ##

echo "BACKUP /public/*"
echo

#mkdir /mnt/backup/public
#cp -auv /public/* /mnt/backup/public/
tar -czvf /mnt/backup/public-$flag.tgz /public
#rsync -a -delete /public/* /mnt/backup/public-$flag

echo "FOLDERS /public/*     BACKED UP"
echo "###############################################"
echo

## UPDATE THE FLAG FILE ON THE DRIVE

#echo $flag >> /mnt/backup/flag  # this line will append the flag var to the file

# The below line will hopefully overwrite the contents of the flag file.
echo $flag > /mnt/backup/flag

sync
sleep 5
## Unmount the back drive
umount /mnt/backup
sleep 5
echo "BACKUP DRIVE UNMOUNTED"
echo "BACKUP OF SYSTEM COMPLETE"
echo

My question is how can I implement a method into this script that will detect or check that the external drive is actually connected.

What happens is when the power fails the backup writes to the local disk and can fill the disk. This happens on occasions that I go away and do not have access to the system.

What I would like to the is have the script automatically check the external drive is connected to the system and if something happens during the running of this backup to terminate the backup.

How do I go about implementing this into my simple backup script?

Guttorm · 04-07-2006, 08:55 AM

Hi

Seems you have a file called "flag" on the disk. Why not simply check if that file is missing?

Something like:

Code:

if [ ! -f /mnt/backup/flag ]
then
  echo "Failed mounting backup disk - no backup done!"
  exit 1
fi

Best Regards,
Guttorm.

bigrigdriver · 04-07-2006, 06:10 PM

There is another possibility that might easily be incorporated into a bash script.

When bash executes a command successfully, the exit code is 0. Any failure results in an exit code other than 0.

Try this test. Run a command you know will succeed, such as copying a file. Immediately after the copy command, run 'echo $?'. The return code is 0. Run a command you know will fail. 'echo $?' return a code other than 0.

So, before starting the backup, try to mount the device that is to receive the backup. If mount fails (device is already mounted), the exit code is not 0. If $? = 0, then abort, else do backup.