How do you overwrite the contents of a file without changing the file size?

lothario · 07-12-2010, 05:29 PM

We have some large files with sampling data in it.
Don't want to delete these files.
But want to quickly overwrite the file with 0s and/or 1s and preserve the original file size.

kbp · 07-12-2010, 05:49 PM

Looks like the ideal job for a secure deletion prog... you can use wipe with these args: 'wipe -ZFke <filename>'

cheers

pixellany · 07-12-2010, 10:22 PM

text data or binary?

For a text file: Use SED to replace every character with something.

Text or binary: If you know the size of the file, then use dd to write all zeros to it.
example: Write all zeros to the file "mystuff":

Code:

filesize=$(stat -c %s mystuff)
dd if=/dev/zero of=mystuff bs=1 count=$filesize

H_TeXMeX_H · 07-13-2010, 08:43 AM

'shred' will work as well.