Postgres backup script (rails focused)

db_backup.sh

# Postgres backup script
# mynameisrufus
#
# Cron tab examples:
#
# daily keeping the last 5 days (run at 1:00AM, 2 minutes after the hour)
#
#    02 1 * * * postgres /script/db_backup.sh daily /var/backups/db $DATABASE_OWNER 5 >> /var/backups/db/backup.log 2>&1
#
#
# weekly keeping the last 2 weeks (3:00AM, Sunday 02 minutes after the hour)
#
#    02 3 * * 0 postgres /script/db_backup.sh weekly /var/backups/db $DATABASE_OWNER 2 >> /var/backups/db/backup.log 2>&1
#
#
# monthly keeping the last 2 months (5:00AM, On the first of the month, 02 minutes after the hour)
#
#    02 5 1 * * postgres /script/db_backup.sh monthly /var/backups/db $DATABASE_OWNER 2 >> /var/backups/db/backup.log 2>&1
#

fail()
{
    echo `date +%h:%m:%s` error: $1
    kill -sigint $$
}

if [ "$1" ]
then
   frequency=$1
else
    fail "frequency missing (arg 1)"
fi

if [ "$2" ]
then
   backup_dir=$2
else
    fail "path to backup dir missing (arg 2)"
fi

if [ "$3" ]
then
    user=$3
else
    fail "user missing (arg 3)"
fi

if [ "$4" ]
then
    keep=$4
else
    fail "number of keeps missing (arg 4)"
fi

before=`date +%s`
printf "\n------------------------------------------------------------------------------\n"
printf "%s: STARTING %s backups ........\n" `date +%h:%m:%s` $frequency

full_path=$backup_dir/$frequency
date=`date +%Y%m%d`
mkdir -p $full_path/$date


ignore="staging|test"

database_list=`psql -l | egrep -v $ignore | grep $user | awk '{print $1}' | grep -v \|`

count=`ls $full_path | egrep "^[0-9]{8}$" | wc -l`

if [ $count -gt $keep ]
then
    remove=`expr $count - $keep`
    directories=`ls $full_path| egrep "^[0-9]{8}$" | sort -n | head -$remove`
    for directory in $directories
    do    
        rm -rf $full_path/$directory
    done
fi

for database in $database_list
do
    database_before=`date +%s`
    printf "%s: creating %s backup for %s\n" `date +%h:%m:%s` $frequency $database
    dump_file="$full_path/$date/$database.gz"
    `pg_dump --no-acl --no-owner --clean $database | gzip > $dump_file`
    database_after=`date +%s`
    database_elapsed_seconds=`expr $database_after - $database_before`
    printf "%s: %s backup for %s finished in %s seconds\n" `date +%h:%m:%s` $frequency $database $database_elapsed_seconds
done

after=`date +%s`
elapsed_seconds=`expr $after - $before`

if [ "$elapsed_seconds" ]
then
   printf "%s: COMPLETED %s backups in %s seconds\n" `date +%h:%m:%s` $frequency  $elapsed_seconds
fi