Problems backing up a folder

Shell Programming and Scripting
1

So I play on a minecraft server that keeps crashing, then rolling back, losing about 30 minutes of data. I don't own the server I'm just writing it for him. So I'm trying to have the script make a back up of the server every 5 minutes as long as it is bigger than the back up, since as more things are done the folder size increases and when it rolls back it decreases.

cd path
worldsize1=[du -s world]
worldsize2=[du -s world]
while [[$worldsize1 -lt $worldsize2 || $worldsize1 -eq $worldsize2]];do
    worldsize1=[du -s world]
    while [[$SECONDS % 300 -ne 0]];do
    done
    mkdir tempworld
    cp world /tempworld/
    cd path/tempworld
    mv world copiedworld
    cd path
    mv tempworld/copiedworld copiedworld
    rmdir tempworld
    worldsize2=[du -s world]
done

The variables path and world are the only things that will be substituted. I'm quite new to this, and I'm coding this for Solaris while running ubuntu.

2

Corrected a few things:

path='/path/to/dir'
cd "$path"
worldsize1=$( du -s world )
worldsize2=$( du -s world )
while [ $worldsize1 -lt $worldsize2 ] || [ $worldsize1 -eq $worldsize2 ];do
    worldsize1=$( du -s world )
    # no need for a loop to wait 5 mins
    # you would be wasting CPU cycle in that way
    sleep 300
    mkdir tempworld
    cp world /tempworld/
    cd path/tempworld
    mv world copiedworld
    cd path
    mv tempworld/copiedworld copiedworld
    rmdir tempworld
    worldsize2=$( du -s world )
done
3

Thanks!