backup.sh

#!/bin/bash
NAME=$1
FROM=$2
PIDFILE=".$1.pid"
DIR=$(pwd)
PERIOD=${3:-7}
PRIORITY=${4:-10}
FILENAME="$(date +%Y-%m-%d_%H%M).tar.gz"
BACKUPDIR="$DIR/backups/$NAME"

echo "Backup Name: $1"
echo "Backup From: $2"
echo "Backup To: $BACKUPDIR"
echo " ... and where the backup file will be created: $BACKUPDIR/$FILENAME"

# check existing process
if [ -f "$PIDFILE" ]
then
    read PID < $PIDFILE
    if ps -p $PID > /dev/null
    then
        echo "backup process is already running.."
        exit 1
    fi
fi

# store PID
echo $$ > $PIDFILE

# create backup template
mkdir -p $BACKUPDIR

# delete old backups
find $BACKUPDIR/ -name "*.tar.gz" -mtime "+$PERIOD" -exec rm {} \;

# backup now
# z: compress archive using gzip, c: create an archive, f: archive filename
nice -n $PRIORITY tar -zcvf "$BACKUPDIR/$FILENAME" $FROM

# delete PID file
rm $PIDFILE