Simple MySQL backup script

gistfile1.sh

#!/bin/bash
# MySQL backup script
# Creates database dump file for each database.
# Created: 2010-09-27

# config
BACKUP_USER=backup
BACKUP_DIR=/var/backups/mysql
LOGFILE=/var/log/mysql_backup

error()
{
    echo $1 1>&2
    exit 1
}
dump()
{
    tmpfile=`mktemp`
    trap "rm -f \"$tmpfile\"; exit 0" SIGINT SIGTERM SIGHUP SIGQUIT

    mysqldump --skip-comments -u "$BACKUP_USER" "$1" > "$tmpfile" 2>>$LOGFILE

    # check dump error code
    if [ $? -gt 0 ];
    then
        rm -f "$2"
        error "Backup failed for $1, see logfile."
    fi  

    # compress file
    bzip2 --best "$tmpfile"
    tmpfile="${tmpfile}.bz2"

    diff=$(diff -N "$tmpfile" "${2}.bz2")
    if [ "$diff" == "" ];
    then
        echo "No need to update: $1"
        rm "$tmpfile"
    else
        mv "$tmpfile" "${2}.bz2"
    
        # set permissions
        chmod 640 "${2}.bz2"
        echo "Dump finished: $1"
    fi  
}

# get all database names except "information_schema"
databases=$(mysql -u "$BACKUP_USER" -NBe "SHOW DATABASES;" | grep -v "information_schema")

# create backup directory if it doesn't exists
mkdir -p "$BACKUP_DIR"
if [ $? -gt 0 ];
then
    error "Cannot create backup directory, exiting"
fi

# for each database
pids=""
for db in $databases;
do
    cur_file="${BACKUP_DIR}/${db}"

#   rm -f "$cur_file.bz2"
    dump "$db" "$cur_file" &
    pids="$pids $!"
done

# wait for all processes to finish
wait $pids