[sminch]

in os x is it possible to open the same app multiple times, so that two (or more) copies of it are running simultaneously?

what i'm wanting to do is have a couple of copies of the same dvd ripper open at once so that i can have them ripping different files at the same time - i can't queue the app to do two or three files in series (so that it'd do them sequentially over a couple of hours), so figured i could do them in parallel on a couple of copies of the app at the same time and come back when they're all done. having to manually select the next file when each of them is finished is a drag.

the thing is, i can't work out how to convince os x to let me do this. is this possible?

sminch

ps - i'm not really interested in a better dvd ripper as this has only been an issue once, but am interested in this as a theoretical question about the os...

[tooki]

The OS has no problem with it.

With many apps, duplicating the application and launching each copy separately works. Other apps don't allow that, and will complain.

You'll just have to try it and see what happens.

tooki

[Krusty]

Yes, OS X can run 2 instances of the same app. Just option-drag the app and it will make a copy called App_Copy. You can run both simultaneously.

One caveat: Apps often have set places where preferences, caches, and temp files are stored and how they are named. Having two instances of the same app may cause unpredictable behavior if they are reading/writing/running from the same set of "support" files.

[Detrius]

This is Unix, so of *COURSE* it's possible. Unfortunately, it requires some command line finagling. In the Macintosh tradition, it is silly to have an application open up a duplicate copy if you double click it, as this wastes resources. In the Unix tradition, though, you may have tar or gzip working on multiple files at the same time--in parallel.

Here's the trick:

Open Terminal. Type 'cd ' -- note the space after 'cd'.
Find your application in the Finder.
Drag the application into your terminal window.
Go back to the terminal window and press [enter]. If the program is Carbon, you will get an error and this method will not work (you'll instead just need to make duplicate copies of the application). If the program is Cocoa, however, you will now be inside the application.
Type: cd Contents/MacOS [enter]
Type: ls [enter] There should only be one file listed, and it should be the exact name of the application (if there are more, that's okay too, but we want the one named after your application).
Type: ./ and enter the name of that file. Then, end the line with &
press enter.
This will launch an instance of your application. At this point, you can repeat the line you just typed and launch another instance.

Magic.

[CharlesS]

Alternatively, if you're running 10.3 or higher, you can usually control-click on the app, choose "Show Package Contents", then navigate to Contents/MacOS and double-click the one file in there. This will usually cause a Terminal window to pop up, followed by an instance of your app (whether or not one is running already or not).

[jamil5454]

Originally posted by Detrius:
This is Unix, so of *COURSE* it's possible. Unfortunately, it requires some command line finagling. In the Macintosh tradition, it is silly to have an application open up a duplicate copy if you double click it, as this wastes resources. In the Unix tradition, though, you may have tar or gzip working on multiple files at the same time--in parallel.

Here's the trick:

Open Terminal. Type 'cd ' -- note the space after 'cd'.
Find your application in the Finder.
Drag the application into your terminal window.
Go back to the terminal window and press [enter]. If the program is Carbon, you will get an error and this method will not work (you'll instead just need to make duplicate copies of the application). If the program is Cocoa, however, you will now be inside the application.
Type: cd Contents/MacOS [enter]
Type: ls [enter] There should only be one file listed, and it should be the exact name of the application (if there are more, that's okay too, but we want the one named after your application).
Type: ./ and enter the name of that file. Then, end the line with &
press enter.
This will launch an instance of your application. At this point, you can repeat the line you just typed and launch another instance.

Magic.

Ahhh... good ol' UNIX tricks. I love OS X.

[sith33]

As an aside, doing what you want to do would be pretty silly. Because CD/DVD drives have such a slow seek time when compared to a harddisk, having two programs fighting over which file to read at a given time from a single disk gets very very ugly. To see for yourself, start playing a DVD in dvdplayer, then try copying a file off the same disk in finder... no fun...

[sminch]

excellent, thank you all! i'll give this a whirl tonight.

sith33 - yip, i've thought of that, and was going to do the ripping off a copy of the dvd on my hd. i think this'll run better, but we shall see...

sminch

[Randman]

For a DVD rip, you'd lose time running the app twice. However, it's very easy to run the same app twice if you have an external HD. I have mine bootable via CCC. Before I got my PB17, I had an IceBook at home with an external DVD burner. For a while, I used that off the external and the PB's SuperDrive to rip some CDs. Then I just imported all of the files into iTunes when I was done.