Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

Please explain the .dmg file

K

kevinliu4

macrumors regular
Original poster
Aug 8, 2006
160
0
i'm new to mac. got my mac this afternoon.

could someone explain the .dmg file. i understand what it stands for but can i just delete it once the program has been installed? in windows terms, all i can gather is that its kinda like a zip and installer exe file in one. i may be way off.

i did a search but couldn't get a clear answer. i also saw the term "mount". what exactly does that mean? if someone can give me an explanation in windows terms, that would be even better ie; what is the windows equivalent if any.

thanks a lot!
 
dpaanlka

dpaanlka

macrumors 601
Nov 16, 2004
4,868
30
Illinois
a dmg file is a disk image file

it functions exactly the same as the windows iso file

when you double click on it, a new "disk" shows up on your desktop, showing you the contents of the dmg file. mac os x treats this as if it were an actual hard drive that you have plugged into your computer. "mounting" is the act of allowing you to see the contents of a hard drive, by putting it onto the desktop. "unmounting" is removing the disk from the desktop, so it may be safely shut off (if it is a physical hard drive), or in the case of a disk image file, so the image can be deleted. you unmount a disk (hard disk, cd-rom, disk image) by dragging it to the trash

once you install the program (usually by dragging it into the applications folder), you can unmount the disk image and delete the dmg file
 
gauchogolfer

gauchogolfer

macrumors 603
Jan 28, 2005
5,551
5
American Riviera
The .dmg acts as a virtual drive. Once 'mounted' (by double clicking) you can drag files to and from like it was a real drive. For installing applications, the typical thing to do is download the .dmg -> mount -> drag application to apps folder -> unmount/eject -> delete .dmg file . The only reason to keep it is if you want to be sure of having it in the future, i.e. to avoid having to update to a newer version if you don't want to. Hope this helps.
 
iGary

iGary

Guest
May 26, 2004
19,580
7
Randy's House
Yes, you can just delete it once the program has installed.

"Mount" means to "hook up" or "connect" a disk, server or othe drive.
 
j26

j26

macrumors 68000
Mar 30, 2005
1,725
613
Paddyland
It's like a mini drive but it's packed up.
When you double click it, it unpacks (mounts) and a new drive opens in the folder you have the dmg in. You can use that drive as normal, or if it's an application you can drag the application into your applications folder and use it from there.
Once that's done you can eject the drive it created and delete the dmg if you want (I usually store them on a CD to save having to download again.

It's also a handy way of sending a load of files, since you can pack them in one dmg for download, and whatever file structure you put them in is intact.
 
K

kevinliu4

macrumors regular
Original poster
Aug 8, 2006
160
0
that's great guys. very clear explanations from all. thanks a lot!

i'm loving my new mac by the way!
 
V

VoodooDaddy

macrumors 65816
May 14, 2003
1,414
0
yes, once you install the app, unmount the virtual drive it creates and delete the dmg file.

A dmg is essentially all the files you would find on any cdrom disc. When you double click the dmg file it creates a virtual disc drive on the desktop just as if you had inserted a physical cdrom disc into a real drive on a windows pc. You install your app, then you eject the virtual drive, just as you would eject the disc from a real drive.

Im not good at explaining things. I hope that was somewhat clear.

edit - wow, before I could get the post done, several beat me to it :)
 
E

elbirth

macrumors 65816
Jan 19, 2006
1,154
0
North Carolina, US
as a pointless aside, I always find myself wanting to call it a "damage" file because I've heard so many Windows people refer to it that way in confusion.

Disk Image, people, Disk Image! :rolleyes:

:cool:
 
N

nicole522

macrumors newbie
Aug 19, 2006
1
0
i'm also new to mac and still having some trouble with my dmg files.

example: i downloaded microsoft messenger (dmg), dragged it to my applications, ejected, and then moved it to the trash. but when i tried to open it in my dock, it appears with a question mark and nothing happens. are you sure you can simply drag these files into the trash and still use them?

:confused:
 
Super Macho Man

Super Macho Man

macrumors 6502a
Jul 24, 2006
505
0
Hollywood, CA
nicole522 said:
i'm also new to mac and still having some trouble with my dmg files.

example: i downloaded microsoft messenger (dmg), dragged it to my applications, ejected, and then moved it to the trash. but when i tried to open it in my dock, it appears with a question mark and nothing happens. are you sure you can simply drag these files into the trash and still use them?

:confused:
Click to expand...
As others in this thread have said, think of a DMG as a disk. When you put a CD into your drive, you don't drag the CD icon to your Applications folder - you drag what's *inside* that CD icon to your applications folder. Same with a DMG. You download the dmg, double-click it, and then a white icon pops up on the desktop. Drag what's *inside* that icon into your Applications folder. Then you can drag both the white icon, and the dmg file, to the trash.

In other words think of the DMG as the box that the product comes in. You open the box by double-clicking it, drag whatever is in the box out of the box, and then trash the box.
 
gauchogolfer

gauchogolfer

macrumors 603
Jan 28, 2005
5,551
5
American Riviera
nicole522 said:
i'm also new to mac and still having some trouble with my dmg files.

example: i downloaded microsoft messenger (dmg), dragged it to my applications, ejected, and then moved it to the trash. but when i tried to open it in my dock, it appears with a question mark and nothing happens. are you sure you can simply drag these files into the trash and still use them?

:confused:
Click to expand...

So, you did the following actions in order?
downloaded the .dmg file to the desktop
double-click .dmg file to mount it
click on mounted .dmg to get inside
find msn application and drag to applications folder
unmount .dmg
erase .dmg file

Then, go to applications folder and start up msn.
 
Cameront9

Cameront9

macrumors 6502a
Aug 6, 2006
961
500
Just FYI, the terms "Mount" and "unmount" are hold-overs from "ye olden days" when you would have to physically mount a reel of tape to the tapedrive in the process of loading it.
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom