scrub

scrub [OPTIONS] special-file ...scrub [OPTIONS] file ...scrub -X [OPTIONS] directory

scrub iteratively writes patterns on files or disk devices to make data recovery more difficult. It operates in three modes:1. Block/character device — the entire device is scrubbed (most effective).2. Regular file — only the file data (and optionally its directory entry name) is overwritten; size is rounded up to the last filesystem block.3. Free space (-X) — creates files under an existing directory until the filesystem is full, then scrubs those files.Default pattern nnsa follows NNSA Policy Letter NAP-14.1-C (two random passes, then 0x00 with verify), which is reasonable for modern PRML/EPRML disks. Other standards include dod, bsi, gutmann, schneier, usarmy, single-pass random/fillzero/fillff, and custom=string.

-v, --version

Print scrub version and exit

Remove the file after scrubbing

Select overwrite patterns (default nnsa). See patterns below

I/O block size in bytes (K/M/G suffixes allowed). Default: 4M

Scrub even if the target already has a scrub signature

Do not write a scrub signature after completion

Fill directory until the filesystem is full, then scrub those files

After scrubbing, overwrite the directory entry name and rename to newname

Override detected device size in bytes (K/M/G allowed)

If target is a symlink, do not scrub the link target (still remove if -r)

Do not use a hardware RNG even if available

Do not generate random data in parallel with I/O

Perform checks and reporting without writing to targets

Print a summary of options

nnsa — 4-pass NNSA: random(x2), 0x00, verify (default)dod — 4-pass DoD 5220.22-M: random, 0x00, 0xff, verifybsi — 9-pass German BSI methodgutmann — 35-pass Gutmann sequenceschneier — 7-pass Schneier: 0x00, 0xff, random(x5)pfitzner7 / pfitzner33 — 7 or 33 random passesusarmy — US Army AR380-19: 0x00, 0xff, randomfillzero / fillff / random / random2 — short fixed or random passesold / fastold — legacy multi-pass sequencescustom=string — one pass with C-style escapes (\xnn, \nnn)

Scrubbing through a filesystem is limited by the OS and filesystem type. Journaled, log-structured, copy-on-write, versioned, and network filesystems may retain prior data elsewhere; prefer scrubbing the raw device when possible.scrub cannot reach blocks remapped/spared by the disk controller. For ATA drives, firmware security erase via hdparm may be more thorough. Physical destruction remains the only strong guarantee against lab recovery.Free-space scrubbing (-X) only helps for blocks the filesystem reassigns to new files. Always verify device size before scrubbing raw devices — wrong targets destroy data irreversibly.

scrub originated at Lawrence Livermore National Laboratory (UCRL-CODE-2003-006) as a GPL disk/file overwrite utility implementing published media sanitization methods (NNSA, DoD, Gutmann, and others).

shred(1), wipe(1), wipefs(8), hdparm(8), dd(1)

Source code · Documentation