The wipe command can be used to securely erase files from magnetic media.
sudo apt install wipe
wipe [options] <target>
Usage: wipe [options] files... Options: -a Abort on error -b <buffer-size-lg2> Set the size of the individual i/o buffers by specifying its logarithm in base 2. Up to 30 of these buffers might be allocated -c Do a chmod() on write-protected files -D Dereference symlinks (conflicts with -r) -e Use exact file size: do not round up file size to wipe possible junk remaining on the last block -f Force, i.e. don't ask for confirmation -F Do not attempt to wipe filenames -h Display this help -i Informative (verbose) mode -k Keep files, i.e. do not remove() them after overwriting -l <length> Set wipe length to <length> bytes, where <length> is an integer followed by K (Kilo:1024), M (Mega:K^2) or G (Giga:K^3) -M (l|r) Set PRNG algorithm for filling blocks (and ordering passes) l Use libc's random() library call a Use arcfour encryption algorithm -o <offset> Set wipe offset to <offset>, where <offset> has the same format as <length> -P <passes> Set number of passes for filename wiping. Default is 1. -Q <number> set number of passes for quick wipe -q Quick wipe, less secure, 4 random passes by default -r Recurse into directories -- symlinks will not be followed -R Set random device (or random seed command with -S c) -S (r|c|p) Random seed method r Read from random device (strong) c Read from output of random seed command p Use pid(), clock() etc. (weakest) -s Silent mode -- suppresses all output -T <tries> Set maximum number of tries for free filename search; default is 10 -v Show version information -Z Do not attempt to wipe file size -X <number> Skip this number of passes (useful for continuing a wiping operation) -x <pass1,pass2,...> Define pass order
wipe -r /media/b/1GB-USB Okay to WIPE 1 directory ? (Yes/No) yes Wiping 1.h2w, pass 0 (0 ) 4305 / 60718] ETA 3h08m