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Empty Trash Securely

A

ayeplussjr

macrumors regular
Original poster
Okay..I went into finder preferences and made sure that empty trash securely was checked so that when I empty the trash it should always do so securely. Well...when I right click on the trash bin and click on empty trash it does not give me the status bar like it would usually do so when I open the trash bin and then click on "empty securely" Even if I just right click on the trash bin and empty trash that way shouldn't it empty the bin securely that way as well?

When I right click on empty trash am I just emptying trash normally?
 
From the impression I get, even though I've got 'empty trash securely' ticked in finder preferences, it is taking considerably less time to empty the trash when right clicking the can and then choosing 'empty trash' then it is if I choose 'Secure empty trash' from the menu bar.

This leads me to believe it's not doing it securely.

I'll have a look in to it for you..
 
Yes, it's definitely not emptying securely on right-click. I just deleted a 4 GB+ file in under a second. I always delete with command+shift+backspace, which definitely does a secure empty.
 
Yeah...I don't think it's emptying trash securely as well by right-clicking. I'll either just do command+shift+backspace or just open up trash and click on empty securely.

I just thought since empty trash securely was clicked in finder preferences that it would automatically empty securely when right-clicking the trash bin as well.
 
The secure empty trash function is very buggy, on one of my computers, it freezes, and on another, it always reads ~40 files in the trash, even if there's only 1 in it. It then gets down to 5 items left to erase, where it hangs.

The best way to secure empty a file is to use the srm function in the terminal.

srm -m -v /file_location_here

-R will erase directories (and sparsebundle files, and applications)
-v shows the percentage complete.
-m is a 7 pass erase. can be replaced with -s for a single pass, -z for a zero out, and can be left out entirely for a 35 pass erase.
 
I hate to reveal my ignorance here, but what is the difference between "empty trash securely" and just emptying the trash? I just did it "securely" and it took several seconds to do so for 18 small items. When I empty it the regular way, it is a snap. Which approach is best and why?
 
mgguy said:
I hate to reveal my ignorance here, but what is the difference between "empty trash securely" and just emptying the trash? I just did it "securely" and it took several seconds to do so for 18 small items. When I empty it the regular way, it is a snap. Which approach is best and why?
Click to expand...
Basically, when you empty the trash OS X just deletes the filename or apart of it to erase the record of it. Since the file is still on the disk if you know what you're doing you can retrieve the file as long as OS X has overwritten it with another file. When you empty the trash securely OS X erases the entire file.
 
QuarterSwede said:
Basically, when you empty the trash OS X just deletes the filename or apart of it to erase the record of it. Since the file is still on the disk if you know what you're doing you can retrieve the file as long as OS X has overwritten it with another file. When you empty the trash securely OS X erases the entire file.
Click to expand...

To clarify, as far as the operating system is concerned the two actions are one and the same, but a moderately determined and resourceful individual can recover insecurely deleted files with little difficulty.
 
QuarterSwede said:
Basically, when you empty the trash OS X just deletes the filename or apart of it to erase the record of it. Since the file is still on the disk if you know what you're doing you can retrieve the file as long as OS X has overwritten it with another file. When you empty the trash securely OS X erases the entire file.
Click to expand...

If it merely erases the names but not the contents of files, after awhile wouldn't this begin to take up a lot of space and eventually even overflow space on your hard drive? Also, if you do a regular erase can you later to a full (secure) erase to get rid of the remaining file contents?
 
mgguy said:
If it merely erases the names but not the contents of files, after awhile wouldn't this begin to take up a lot of space and eventually even overflow space on your hard drive?
Click to expand...

No. QuarterSwede's description is somewhat simplified. When you normally empty the trash, it erases only the information the system uses to access the file on the drive. As far as the system is concerned, where the file was located is now blank space and can be overwritten as the need dictates. This phenomenon is known as data remanence.

mgguy said:
Also, if you do a regular erase can you later to a full (secure) erase to get rid of the remaining file contents?
Click to expand...

Yes. Open Disk Utility, select the hard drive partition in question (Macintosh HD, for example), go to the Erase page, and click Erase Free Space. It will take a while to do so, though, so in the end it's faster to securely empty the trash at the time of deletion.
 
I remember reading when 10.3 came out that that version of Mac OS X and later would write random zeroes and ones to the sector of a hard drive where an erased file was located. Is this true, or is it only done when you Secure Empty Trash? If you don't SET, is the file only completely removed when you write new files to take its space or is it gone after a restart?
 
srm (secure empty trash) Terminal Command Info?

Jethryn Freyman said:
The secure empty trash function is very buggy, on one of my computers, it freezes, and on another, it always reads ~40 files in the trash, even if there's only 1 in it. It then gets down to 5 items left to erase, where it hangs.

The best way to secure empty a file is to use the srm function in the terminal.

srm -m -v /file_location_here

-R will erase directories (and sparsebundle files, and applications)
-v shows the percentage complete.
-m is a 7 pass erase. can be replaced with -s for a single pass, -z for a zero out, and can be left out entirely for a 35 pass erase.
Click to expand...

Can you explain how to enter the "file location" information please? Thanks 😕
 
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