Backup script not working

[Mike2K]

Hi all,

I'm trying to write my first shell script and I've ran into a problem which I can't seem to solve so I thought I'd try my luck here...

I think it's not that hard, but I'm pretty clueless atm so I hope someone can help me.

The code:

#!/bin/sh -x

#################################################################
# Author : Michel van Son														#
# Company : Phison Technologies													#
# Date : 11-05-2008															#
# Purpose : Prepare system for backup by dumping databases and copy websites						#
# Changes: [DD-MM-YYYY] Name - company : changes										#
#################################################################

BACKUP_DIR=/var/backup
ROOT_UID=0
E_NOTROOT=67
STAMP= date "+%Y%m%d"
BACKUP_NUMBER= date "+%k"
HOSTNAME=hostname

# Check if user is root
if [ "$UID" != "$ROOT_UID" ]; then
	echo "Must be root to run this script."
	exit $E_NOTROOT
fi

# Check if /var/backup exists
if [ -e "$BACKUP_DIR" ]; then
	echo "Found: $BACKUP_DIR"
else
	echo "$BACKUP_DIR does not exist, so I'll create it for you."
	mkdir /var/backup
fi

# Dump all databases
mysqldump -uroot -ppassword --all-databases> "$BACKUP_DIR/$STAMP_$BACKUP_NUMBER_$HOSTNAME_mysqlbackup.sql"

# Create website archive
tar -czf "$BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_websites.tar.gz" /var/www

# Remove old backups
BACKUP_NUMBER=$BACKUP_NUMBER-1
if [ -e $BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_mysqlbackup.sql ]; then
	rm $BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_mysqlbackup.sql
else
	echo "No previous SQL backup present. Please verify."
fi
if [ -e $BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_websites.tar.gz ]; then
	rm "$BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_websites.tar.gz"
else
	echo "No previous web backup present. Please verify."
fi

When I run this code in Debian I can see that the file name gets cut off after $BACKUP_DIR/ so I think I need to escape the / but I've tried all kinds of variations with double and single quotes but to no avail...

Does anyone know what I'm doing wrong ?

[bigtomrodney]

It looks like the problem is in your variable setting. If you want $STAMP etc. to be populated you need to have the commands evaluated, otherwise they will be treated as literal strings.

Change your variable section like so

BACKUP_DIR=/var/backup
ROOT_UID=0
E_NOTROOT=67
STAMP=$(date +%Y%m%d)
BACKUP_NUMBER=$(date +%k)
HOSTNAME=$(hostname)

Also, you shouldn't need the quotes for the date command in this case.

[Mike2K]

Thanks for the fast reply BigT.

You are partially right. I changed the script into this:

#!/bin/sh -x

#################################################################
# Author : Michel van Son														#
# Company : Phison Technologies													#
# Date : 11-05-2008															#
# Purpose : Prepare system for backup by dumping databases and copy websites						#
# Changes: [DD-MM-YYYY] Name - company : changes										#
#################################################################

BACKUP_DIR=/var/backup
ROOT_UID=0
E_NOTROOT=67
STAMP=$(date +%Y%m%d)
BACKUP_NUMBER=$(date +%k)
HOSTNAME=$(hostname)

# Check if user is root
if [ "$UID" != "$ROOT_UID" ]; then
	echo "Must be root to run this script."
	exit $E_NOTROOT
fi

# Check if /var/backup exists
if [ -e "$BACKUP_DIR" ]; then
	echo "Found: $BACKUP_DIR"
else
	echo "$BACKUP_DIR does not exist, so I'll create it for you."
	mkdir $BACKUP_DIR
fi

# Dump all databases
mysqldump -uroot -ppassword --all-databases> $BACKUP_DIR/$STAMP_$BACKUP_NUMBER_$HOSTNAME_mysqlbackup.sql

# Create website archive
tar -czf $BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_websites.tar.gz /var/www

# Remove old backups
BACKUP_NUMBER=$BACKUP_NUMBER-1
if [ -e $BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_mysqlbackup.sql ]; then
	rm $BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_mysqlbackup.sql
else
	echo "No previous SQL backup present. Please verify."
fi
if [ -e $BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_websites.tar.gz ]; then
	rm $BACKUP_DIR/$STAMP_$BACKUPNUMBER_$HOSTNAME_websites.tar.gz
else
	echo "No previous web backup present. Please verify."
fi

exit

I can see that the variables are being assigned the right values.
This is the output:

+ BACKUP_DIR=/var/backup
+ ROOT_UID=0
+ E_NOTROOT=67
++ date +%Y%m%d
+ STAMP=20080511
++ date +%k
+ BACKUP_NUMBER=23
++ hostname
+ HOSTNAME=psnnl01s005
+ '[' 0 '!=' 0 ']'
+ '[' -e /var/backup ']'
+ echo 'Found: /var/backup'
Found: /var/backup
+ mysqldump -uroot '-ppassword' --all-databases
+ tar -czf /var/backup/.tar.gz /var/www
tar: Removing leading `/' from member names
+ BACKUP_NUMBER=23-1
+ '[' -e /var/backup/.sql ']'
+ rm /var/backup/.sql
+ '[' -e /var/backup/.tar.gz ']'
+ rm /var/backup/.tar.gz
+ exit

I also tried escaping the filename string but that doesn't seem to make a difference...What is going wrong ?

[bigtomrodney]

Right I found a couple of things. First thing is that the underscores don't act as delimiters, so it helps to quote the variables when concatenating them together so they are parsed correctly. The second thing is you missed a few underscores too in your variable names ($BACKUP_NUMBEr vs. $BACKUPNUMBER). I'm posting the debug script I used as is because I'm off to bed now. Also, I commented out the root check as I ran it as a normal user...

#!/bin/sh -x

#Author : Michel van Son														#
# Company : Phison Technologies													#
# Date : 11-05-2008															#
# Purpose : Prepare system for backup by dumping databases and copy websites						#
# Changes: [DD-MM-YYYY] Name - company : changes										#
#################################################################

export BACKUP_DIR=/home/bigtomrodney/testbackup
export ROOT_UID=0
export E_NOTROOT=67
export STAMP=$(date +%Y%m%d)
export BACKUP_NUMBER=$(date +%k)
export HOSTNAME=$(hostname)

echo BACKUP_DIR $BACKUP_DIR
echo ROOT_UID $ROOT_UID
echo E_NOROOT $E_NOTROOT
echo STAMP $STAMP
echo BACKUP_NUMBER $BACKUP_NUMBER
echo HOSTNAME $HOSTNAME
echo 1 String set as :- $BACKUP_DIR/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_websites.tar.gz

# Check if user is root
#if [ "$UID" != "$ROOT_UID" ]; then
#	echo "Must be root to run this script."
#	exit $E_NOTROOT
#fi

# Check if /var/backup exists
echo Check if /var/backup exists
if [ -e "$BACKUP_DIR" ]; then
	echo "Found: $BACKUP_DIR"
else
	echo "$BACKUP_DIR does not exist, so I'll create it for you."
	mkdir $BACKUP_DIR
fi

# Dump all databases
echo Dump all databases
mysqldump -uroot -ppassword --all-databases> "$BACKUP_DIR"/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_mysqlbackup.sql

# Create website archive
echo Create website archive
echo 2 String set as :- "$BACKUP_DIR"/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_websites.tar.gz
tar -czf "$BACKUP_DIR"/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_websites.tar.gz /home/bigtomrodney/Support

# Remove old backups
echo Remove old backups
BACKUP_NUMBER=$BACKUP_NUMBER-1
if [ -e "$BACKUP_DIR"/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_mysqlbackup.sql ]; then
	rm "$BACKUP_DIR"/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_mysqlbackup.sql
else
	echo "No previous SQL backup present. Please verify."
fi
if [ -e "$BACKUP_DIR"/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_websites.tar.gz ]; then
	rm "$BACKUP_DIR"/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_websites.tar.gz
else
	echo "No previous web backup present. Please verify."
fi

exit

[i92guboj]

I haven't looked too deep into that script so I don't really know which is the problem. However, I just wanted to drop a quick note:

"$BACKUP_DIR"/"$STAMP"_"$BACKUP_NUMBER"_"$HOSTNAME"_websites.tar.gz

You can just quote the whole lot, there's no need to go quoting every single variable.

"$BACKUP_DIR/$STAMP_$BACKUP_NUMBER_$HOSTNAME_websites.tar.gz"

However, this will fail as well because there's another problem: you are not delimiting the variables the right way. To avoid such problem, you use curly brackets this way:

"${BACKUP_DIR}/${STAMP}_${BACKUP_NUMBER}_${HOSTNAME}_websites.tar.gz"

[bigtomrodney]

The idea of using the quotes was simply to delimit the variables. Given the nature of the variables and strings, if you use brackets for delimiting you shouldn't require quotes at all.

[Mike2K]

Thanks for the help.

The curly brackets did the trick. Now I'm struggling with the substraction.
I'm getting a "command not found" when I try to substract 2 from the $BACKUP_NUMBER.

Thanks for all the help...It was a bit harder then I thought...

[i92guboj]

The idea of using the quotes was simply to delimit the variables. Given the nature of the variables and strings, if you use brackets for delimiting you shouldn't require quotes at all.

That's of course false.

$ VAR="p p"
$ LC_ALL=C ls -l ${VAR}
ls: cannot access p: No such file or directory
ls: cannot access p: No such file or directory

You can see how the ls will treat ${VAR} as a list with two arguments. In the contrary, if you quote as you must, then you get only one:

$ LC_ALL=C ls -l "${VAR}"
ls: cannot access p p: No such file or directory

The brackets are only a way to guarantee that the variable name doesn't get mixed with any stuff around it, but it doesn't delimit strings. The two mechanisms are closely related but are not quite the same.

[bigtomrodney]

I think you misunderstood the context of what I was saying. I am not talkling general usage but in the particular case above. There is no whitespace in any of the variables in that script which is why I said "Given the nature of the variables and strings...". In that case you do not require strings around the longer filepath/filename string as you are delimiting the data using brackets already.

"${BACKUP_DIR}/${STAMP}_${BACKUP_NUMBER}_${HOSTNAME}_websites.tar.gz"

The brackets are only a way to guarantee that the variable name doesn't get mixed with any stuff around it, but it doesn't delimit strings.

That is exactly what it is doing, it is setting the boundaries within the overall string that define what is a variable and what is not. That is exactly what delimiting is, establishing limits or boundaries

The two mechanisms are closely related but are not quite the same.

I agree completely, and the example of the code I gave was for the case in question, not a general HOWTO for variables. I found it to be suitable as there was no whitespace, and overall there is no difference in character count between the two methods. I would certainly agree that your bracket method would be the preferred method for general usage.

[Mike2K]

Thanks for clearing that up...Does anyone know how I can substract 2 from the variable $BACKUP_NUMBER?

just $SOMETHING = $BACKUP_NUMBER - 2 doesn't seem to work...