rsync, keeping two folders in sync

Shazkar Shadowstorm

hi

simple question

i run os x

i have a folder on one external hard drive
i would like it to be sync'd to another external hard drive, so in case one dies it survives

what is the easiest way to do this? how does rsync work?

admanb

You'll want to setup a cron job or other automation of a shell script. The basic command is just rsync <folder a> <folder b> but you'll probably want to do -raz --delete (recursive, duh; archive, which copies permissions and such; compress, which reduces the transfer size; and --delete makes sure that any files you delete in the source are deleted in the destination.

Lewisham

Any reason why you can't use Time Machine for the job? That way it'll have the folder versioned too.

Echo

Can Time Machine do individual folders then? I've only ever seen entire volume versioning.

Anyway, you want Folder Actions. Right click folder -> More -> Folder Actions. You'll probably have to make the script yourself though, or find one somewhere.

It'll run automatically when the folder changes, no need to wait for cron to kick in and run rsync.

edit: on some further googling, it appears that Folder Actions only trigger when files are created/deleted, not modified.

admanb

Time Machine just does exclusions, so it's designed to be a complete system backup (minus anything you don't particularly care for) that you can restore to.

Annoyed me when I realized I wouldn't be able to use it to keep my docs and stuff backed up to my external HD. 'course, that died months ago and I can't afford to replace it, so I suppose it worked out.

Echo

It's not really what the OP asked for, but I keep the important stuff in Dropbox (disclaimer: that's a referral link, but you get both me and yourself an extra 250 megs of storage through it), which syncs it on two different computers as well as online, with built-in versioning.

Shazkar Shadowstorm

yeah, i use time machine for my computer's hard drive, this is between two external hard drives, none of this data is on my actual computer, i just want it to be redundant (lotta music and stuff i care about)

sorry for my ignorance, any tutorial or something about writing a cron script? im mildly familiar with shell scripting but not a ton

edit:

Echo wrote: »

It's not really what the OP asked for, but I keep the important stuff in Dropbox (disclaimer: that's a referral link, but you get both me and yourself an extra 250 megs of storage through it), which syncs it on two different computers as well as online, with built-in versioning.

yeah, i have dropbox dude, but this is a 90 GB folder i'm talking about anywho

Echo

Assuming standard Unix structure: poke at /etc/crontab.

*/5 * * * * /home/user/foo.pl

That's the format. This runs every 5 minutes. Here's the syntax. Very easy.

Shazkar Shadowstorm

how do i get the path for my folder anyway? the location is /Volumes/External Drive/folder name

and then the other one would be /Volumes/External Drive 2/folder name

err i am sorry i am so noob

admanb

What do you mean? The main thing you have to do is backslash-escape the spaces. So the first one would become

/Volumes/External\ Drive/folder\ name

Shazkar Shadowstorm

but what i mean is how do you get to the very root, because ~ would just get me to
/Users/myusername/

and i need something in

/Volumes

Lewisham

No-one has told you to use a tilde, just specify the paths as you have been writing them out.

You are being very confusing

admanb

Shazkar Shadowstorm wrote: »

but what i mean is how do you get to the very root, because ~ would just get me to
/Users/myusername/

and i need something in

/Volumes

~/ is just an alias for /Users/<your user>

/ is root.

Shazkar Shadowstorm

ah got it