In Finder, I've noticed that if I duplicate some .app files (in the Applications folder), Finder will show that the duplicate .app file is not the same size as the original. This file size discrepancy does not happen for all .app files that I duplicate, but it seems like the larger the .app file, the more likely that the duplicate will not show the same size as the original. Here are some examples:
GarageBand.app - 381.7 MB GarageBand copy.app - 373.2 MB iMovie.app - 695.3 MB iMovie copy.app - 635.4 MB Install Xcode.app - 1.81 GB Install Xcode copy.app - 1.57 GB
Now I am new to Macs, and after I noticed this file size discrepancy problem, I discovered that .app files are actually not files - they are really directories, but Finder displays them as if they are files. So I thought maybe the duplication process did not copy all of the contents of the original .app directory and that explained the difference in "file size". But then I downloaded and installed DeltaWalker, which is a file/folder diff tool, and DeltaWalker said that the duplicate .app directories were exactly the same as the original .app directories. So the duplication process worked perfectly, and it therefore seems to be a problem with Finder reporting file sizes.
I also checked the sizes of the directories in Terminal, using the "du" command, and that too shows discrepancies in sizes between the original and duplicate directories:
du -k /Applications/GarageBand.app/ 212868 /Applications/GarageBand.app/ du -k /Applications/GarageBand\ copy.app/ 397880 /Applications/GarageBand copy.app/ du -k /Applications/iMovie.app/ 629644 /Applications/iMovie.app/ du -k /Applications/iMovie\ copy.app/ 700500 /Applications/iMovie copy.app/ du -k /Applications/Install\ Xcode.app/ 1771864 /Applications/Install Xcode.app/ du -k /Applications/Install\ Xcode\ copy.app/ 1772228 /Applications/Install Xcode copy.app/
Also, it's not just .app directories. I duplicated my /Developer/Library directory, and here's what du said:
du -k /Developer/Library/ 320784 /Developer/Library/ du -k /Developer/Library\ copy/ 399868 /Developer/Library copy/
So can anyone explain why Mac OS X doesn't seem to report directory sizes correctly? Is it a bug (hard to believe for something so simple), or am I missing something (being a new Mac user)?
(I'm running Mac OS X Lion 10.7.2)
UPDATE in response to elofturtle:
What is most strange about this is that Finder has no consistency. I just made 2 duplicates of the GarageBand.app, and then made 2 duplicates of one of the duplicates. Finder displays every single duplicate with a different size:
GarageBand.app - 381.7 MB GarageBand copy.app - 357.6 MB (duplicate of GarageBand.app) GarageBand copy 2.app - 353.9 MB (duplicate of GarageBand.app) GarageBand copy 3.app - 378.2 MB (duplicate of GarageBand copy 2.app) GarageBand copy 4.app - 329.1 MB (duplicate of GarageBand copy 2.app)
Also note that "GarageBand copy 3.app" is larger than "GarageBand copy 2.app", while "GarageBand copy 4.app" is smaller than "GarageBand copy 2.app". That has to be a bug in Finder.
Here's what "du -k" says about all of them:
212868 /Applications/GarageBand.app/ 397880 /Applications/GarageBand copy.app/ 397880 /Applications/GarageBand copy 2.app/ 397880 /Applications/GarageBand copy 3.app/ 397880 /Applications/GarageBand copy 4.app/
At least it says all the duplicates are the same size, but they're not the same size as the original.