bash backup script

[dwanders]

Do any of you guru's see anything potentially bad/harmful with the following script I have been working on to use as a backup script (any and all suggestions/comments greatly appreciated):

I am sure it could be written much more efficiently, but my main concerns are with things that could whack up my system or leave me with an unreliable backup script.

#!/bin/bash
# This is a simple bash script to backup files on
# the home computer. The backup system uses a spare
# HDD for the backup media rather than tape.
#
# It is intended to be run from cron like:
# (30 11 * * * backup.sh 2>log.file)
# The 2 above will only send stderr to the log
#
# The idea is to:
# 1) Mount a backup media drive (exit if fail)
# 2) Verify target file exists (exit if fail)
# 3) parse through target file
# 4) if new target
# a) tar the target files up
# b) gzip the new target
# 5) if not new, update the current tar file by
# a) gunzip the archive
# b) run tar update
# c) gzip the file
# 6) Unmount the backup file system
# 7) verify un-mount
# 8) exit script
# echo date for start of log file
/bin/date

# Static global variables
backup_path=/mnt/backup/

#Begin Backup Functions
function check_target {
if [ -f bu_targets.txt ];
then
echo "Target file exists."
echo "... continuing ..."
else
echo "Cannot find target file."
echo "... exiting ..."
exit 0
fi
}

function mount_drive {
# Mount the data hard drive
mount /dev/sdb1 /mnt/backup
}

function check_mount {
# Check that the mount succeded
if [ -a /mnt/backup/mount_test ];
then
echo "Mount seemed to work."
echo "... continuing ..."
else
echo "Mount failed."
echo "... exiting ..."
exit 0
fi
}

function archive_targets {
# Begin archiving/updateing targets
while read line;
do
PATH=${line%;*};
ARCH_NAME=${line#*;};
if [ -f "$backup_path$ARCH_NAME.tar.gz" ];
then
echo "The file $backup_path$ARCH_NAME.tar.gz exists"
echo "start update process of: gunzip then tar update then gzip"
/bin/gunzip $backup_path$ARCH_NAME.tar.gz && /bin/tar uvf $backup_path$ARCH_NAME.tar $PATH/* && /bin/gzip $backup_path$ARCH_NAME.tar
else
echo "The file does not seem to exist"
echo "start process to create new tar file, gzip file"
/bin/tar cvf $backup_path$ARCH_NAME.tar $PATH/* && /bin/gzip $backup_path$ARCH_NAME.tar
fi
done <bu_targets.txt
}

function unmount_drive {
#Un-mount & verify un-mount of the spare file system
echo "Un-Mounting"
/bin/umount /mnt/backup

# Verify unmount success
while [ -a /mnt/backup/mount_test ]
do
echo "Un-Mount must have failed";
echo "... sleeping for 30 seconds, then trying again ...";
/bin/sleep 30;
echo "... trying again ...";
/bin/umount /mnt/backup;
done

echo "BackUp drive unmounted.";
echo "... continuing ...";
}

function exit_script {
#echo end date for log file & status
/bin/date
exit 1
}

# Start Main program Execution
check_target
mount_drive
check_mount
archive_targets
unmount_drive
exit_script

The above uses another file for the targets, that is like:
/etc;system_etc
/root;system_root

Again, any suggestions or input is greatly appreciated.

[Ramses de Norre]

In your exit function, I think you mean exit 0 instead of exit 1, 1 is an erroneous exit and 0 is a correct/normal exit.

[dwanders]

I changed my 1's to 0's and 0's to 1's - thanks.

I also found out that for some reason the gzipped files in the end had bad crc's and would not open. So I added another 30 second sleep and it seemed to clear up. Also changed my tar command to:

/bin/gunzip $backup_path$ARCH_NAME.tar.gz
&& /bin/tar uvf $backup_path$ARCH_NAME.tar -P --totals $PATH/*
&& /bin/gzip $backup_path$ARCH_NAME.tar
else
echo "The file does not seem to exist"
echo "start process to create new tar file, gzip file"
/bin/tar cvf $backup_path$ARCH_NAME.tar -P --totals $PATH/*
&& /bin/gzip $backup_path$ARCH_NAME.tar

And it now seems to be working fine. Any other suggestions/comments still greatly appreciated.

[dwanders]

I think I have determined that I had way too many ;'s in that script - so I removed the excess. Now I am wondering, is there a way I can check each step to ensure that it completes without problems e.g. after the tar, and each gunzip?