"Na ext3/4 (nevím jestli to bylo i na ext2) se ale skutečně fyzicky přemažou celé soubory a všechny binární hodnoty v jejich bývalém umístění se nastaví na "0""
to neni pravda, protoze by to napr. znamenalo, ze by nemohly fungovat recovery programy jako photorec
priklad:
# echo FIRZEN > file.txt
# zjistim kde se nachazi file.txt na disku
# filefrag -vs file.txt
Filesystem type is: ef53
File size of file.txt is 7 (1 block, blocksize 4096)
ext logical physical expected length flags
0 0 2141060 1 eof
file.txt: 1 extent found
# je tam
# dd if=/dev/sda5 count=1 bs=4096 skip=2141060 | hd
00000000 46 49 52 5a 45 4e 0a 00 00 00 00 00 00 00 00 00 |FIRZEN..........|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00001000
1+0 records in
1+0 records out
4096 bytes (4.1 kB) copied, 0.000632314 s, 6.5 MB/s
# vymazu
# rm -f file.txt
# cat file.txt
cat: file.txt: No such file or directory
# sync
# furt je tam :)
# dd if=/dev/sda5 count=1 bs=4096 skip=2141060 | hd
00000000 46 49 52 5a 45 4e 0a 00 00 00 00 00 00 00 00 00 |FIRZEN..........|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00001000
1+0 records in
1+0 records out
4096 bytes (4.1 kB) copied, 0.000414184 s, 9.9 MB/s