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I’ve got an internal SSD on a 2018 MBP, with these drives macOS no longer gives you the option to secure erase the trash.

I’ve connected an older HDD external drive which I wish to secure erase the trash on, how can i do this in OSX 10.13 ?

Allan
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sam
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2 Answers2

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To securely “empty” the trash on an external drive you can use the rm command with the -P option which will overwrite it 3 times - similar to a DoD 3-pass overwrite.

% rm -P /Volumes/foo/bar/.Trash/*

The other option is to reinstall srm via Homebrew or Macports and use srm in place of rm

% srm  /Volumes/foo/bar/.Trash/*

You could even create an alias and put it in your .zprofile or .bash_profile depending on the shell you’re using.

alias emptytrash=‘rm -P /Volumes/foo/bar/.Trash/*’
Allan
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  • Note: This answer does not work for modern macos. According to the macos 14.3.1 man page for rm:

    -P This flag has no effect. It is kept only for backwards compatibility with 4.4BSD-Lite2.

    Therefore using -P is no more secure than not using it.

     – Krolaw Feb 19 '24 at 18:23
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Secure erase relies on writes replacing the data in the blocks allocated for a file. With SSDs this is technically not possible. If you want to protect data on an external drive, you need to encrypt it (can be done with a right-click on the drive in Finder).

PS: encrypting external drives is advisable in general, otherwise anybody with physical access to the drive can access its content.

nohillside
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