Need confirmation from someone who knows their stuff...

[mtfield]

So today has been a pretty interesting day for me as a mac owner.. Earlier today I was on my computer and in finder under the HD there was this new file called "usr" I thought it was some random file that got added when I downloaded this thing for my school the previous night and I deleted it. Well it crashed my computer... I called apple and they told me that is a system file that is supposed to remain hidden, but for some unknown reason it stopped being hidden. They told me to go to a store and a genius would reload the OS. So, that's what I did... to make a long story short the genius told me he could reload the OS without erasing the hd so I could keep all my stuff that was on it (documents, movies, pictures, etc.) it worked and the computer is back up and running... but now I see that in finder under the HD there is something called "Previous Systems" now i'd like to delete it because it's 11gb but i'm afraid to for obvious reasons... when I moved it to the trash it came up saying it needed me to type in my password to delete it, which is what the other thing said right before i crashed my computer... so can I delete it and be ok? Thanks for your help!

 

[swiftaw]

Yes, you can delete it.

 

[aristobrat]

I've never had any problems deleting the Previous Systems folder after an Archive and Install installation of OS X.

 

[richard.mac]

you can definately delete the previous systems folder but have a look thru it first to see if you need any of the files that werent migrated over.

as a lesson and just so you dont accidently delete any critical system files or folders anymore, Mac OS X is FreeBSD based and so it is a Unix operating system.

in the root directory, which is called "Macintosh HD" in Mac OS X and "/" in Unix, there are files and folders which are critical to the OS like the kernel and Unix's exceutables and man pages etc. these are usually hidden and can be seen by typing this command into Terminal which is found in the Utilities folder inside the Applications folder.

cd /; ls -a

or by typing this command to see the files in Finder. (replace "TRUE" with "FALSE" to rehide them.)

defaults write com.apple.finder AppleShowAllFiles TRUE; killall Finder

files and folders are hidden in OS X by either having a period before their name or being set as hidden thru Unix. if a critical file without a period before its name like mach_kernel or folders like usr, sbin, private etc. become visible again type "chflags" into Terminal followed by the files directory e.g. for usr

chflags nohidden /usr

 

[mtfield]

I've decided to keep away from the whole terminal side of my computer after today... the weird part is that i've never touched terminal before so i have no idea how those files became unhidden... thoughts?

 

[richard.mac]

your OS just had a little quirk. nothing too drastic.

youll be fine if you input the commands in my first post.

 

[richard.mac]

haha just did a "sudo rm -rfv /" on my Tiger install and after a long print of text everything froze and dock items and menus where missing letters.

i then went back into Leopard and saw the only things left in my Tiger partition where /automount/servers/, /automount/static/ and /Users/tiger/Library/Preferences/com.apple.finder.plist .