TAR doesn't work properly with the crontab - bash

Question

First of all, I'm saying that it doesn't work properly with the crontab because when I run the script manually it works fine.
The problem is that when I run the backup script with the cronjob and... it's coming to tar up the mysql dump, the tar archive has only 16 bytes size (and its empty, so it looks like there were no files to pack into the archive), the strange thing about that is that when I run the script manually, it runs almost 5~ minutes, and the tar package size is ~1.8GB.
Here is my bash code:
#!/usr/local/bin/bash
# Configuration
BACKUPD="/backup/mysql"
MySQLuser='root'
MySQLpass='xxxx'
# End configuration
ROK=`date +%Y`
MIESIAC=`date +%m`
DZIEN=`date +%d`
GIM=`date +%H-%M`
if [ -d $BACKUPD/$ROK/$MIESIAC/$DZIEN ]
then
echo
else
mkdir -p $BACKUPD/$ROK/$MIESIAC/$DZIEN
fi
for db in $(echo "SHOW DATABASES;" | mysql --user=$MySQLuser --password=$MySQLpass | grep -v -e "Database" -e "information_schema")
do
mysqldump --skip-lock-tables --ignore-table=log.log --user="$MySQLuser" --password="$MySQLpass" $db >$BACKUPD/$ROK/$MIESIAC/$DZIEN/$db.sql
done
cd $BACKUPD/$ROK/$MIESIAC/$DZIEN && tar jcPf $BACKUPD/$ROK/$MIESIAC/$DZIEN/mysql-$GIM.tar.bz2 *.sql && rm -rf *.sql
Where is the problem? Did anyone experienced a problem like this before?
Regards.

Answer 1

Can you try with full path name for mysqldump and mysql inside your script.
So:
if which mysql is equal to /usr/local/mysql/bin/mysql
and
if which mysqldump is equal to /usr/local/mysql/bin/mysqldump
Modify your script to:
for db in $(echo "SHOW DATABASES;" | /usr/local/mysql/bin/mysql --user=$MySQLuser --password=$MySQLpass | grep -v -e "Database" -e "information_schema")
do
/usr/local/mysql/bin/mysqldump --skip-lock-tables --ignore-table=log.log --user="$MySQLuser" --password="$MySQLpass" $db >$BACKUPD/$ROK/$MIESIAC/$DZIEN/$db.sql
done

Answer 2

My guess is that the last line is your problem. The shell glob (*.sql) in:
cd $BACKUPD/$ROK/$MIESIAC/$DZIEN && tar jcPf $BACKUPD/$ROK/$MIESIAC/$DZIEN/mysql-$GIM.tar.bz2 *.sql && rm -rf *.sql
is expanded in the current directory and not after the cd as you might expect. Try the following instead, it is safer.
old_dir=`pwd`
cd "$BACKUPD/$ROK/$MIESIAC/$DZIEN"
tar jcPf mysql-$GIM.tar.bz2 *.sql
rm -fr *.sql
cd "$old_dir"
There still might not be any .sql files to tar ball. I don't have mysql installed but I suspect that the for loop is messed up as well. Try something like the following instead:
mysqlshow | \
xargs mysqldump --databases | \
bzip2 > $BACKUPD/$ROK/$MIESIAC/$DZIEN/mysql-$GIM.bz2
You will probably beed to insert other arguments for the mysqlshow and mysqldump commands. Of course this won't create a tarball but it will give you a compressed backup.