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c13f2477b1
This commit updates both README.md and the nwipe(8) manpage to reflect the features and behaviour introduced in the upcoming v0.40 release. Changes include: - Added documentation for the new AES-256-CTR PRNG and its hardware-accelerated implementation. - Updated erasure method list to include the BMB21-2019 State Secrets Bureau sanitisation standard. - Added full documentation for large, aligned I/O buffers and their impact on performance. - Documented the new I/O mode system (`--io-mode=auto|direct|cached`, `--directio`, `--cachedio`) and the interaction with O_DIRECT fallback logic. - Updated sync behaviour description to match the new byte-accurate scaling for cached I/O. - Updated PRNG section to remove the “future release” note for AES-CTR. - Documented improved device exclusion with `/dev/disk/by-id/*` support. - Updated seeding description to reflect the use of `getrandom()` instead of `/dev/urandom`. - Refreshed dependency lists and provided concise installation instructions for multiple Linux distributions. - Minor stylistic cleanup, clarification of SSD limitations, and improved README structure for readability and accuracy.
226 lines
7.5 KiB
Groff
226 lines
7.5 KiB
Groff
.TH NWIPE "8" "Sep 2025" "nwipe version 0.39" "User Commands"
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.SH NAME
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nwipe \- securely erase disks
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.SH SYNOPSIS
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.B nwipe
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[\fIoptions\fR] [\fIdevice1\fR] [\fIdevice2\fR] ...
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.SH DESCRIPTION
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nwipe is a command that will securely erase disks using a variety of
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recognized methods. It is a fork of the dwipe command used by Darik's Boot
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and Nuke (DBAN). nwipe is included with partedmagic if you want a quick and
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easy bootable CD version. nwipe was created out of a need to run the DBAN
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dwipe command outside of DBAN, in order to allow its use with any host
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distribution, thus giving better hardware support. It is essentially the
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same as dwipe, with a few changes:
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.TP
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- pthreads is used instead of fork.
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.TP
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- The parted library is used to detect drives.
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.TP
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- The code is designed to be compiled with gcc.
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.TP
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- SIGUSR1 can be used to log the stats of the current wipe.
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.TP
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- Additional wiping methods and PRNGs.
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.TP
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- Configurable I/O modes (cached, direct, auto) using large I/O buffers for higher throughput.
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.TP
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- Support for stable device paths such as \fI/dev/disk/by-id/\fR.
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.PP
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All PRNG implementations are seeded using the Linux
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.BR getrandom (2)
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system call instead of reading from
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.IR /dev/urandom
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via a file descriptor.
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.SH DEVICES
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.PP
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Devices can be specified either as block device nodes (for example
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.IR /dev/sda ,
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.IR /dev/nvme0n1 ,
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.IR /dev/mapper/cryptroot )
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or via stable symlinks under
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.IR /dev/disk/by-id/ .
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nwipe will resolve these paths and operate on the underlying block device.
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.SH OPTIONS
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.TP
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\fB\-V\fR, \fB\-\-version\fR
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Prints the version number.
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.TP
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\fB\-h\fR, \fB\-\-help\fR
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Prints a help summary.
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.TP
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\fB\-\-autonuke\fR
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If no devices have been specified on the command line, starts wiping all
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devices immediately. If devices have been specified, starts wiping only
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those specified devices immediately.
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.TP
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\fB\-\-autopoweroff\fR
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Power off system on completion of wipe delayed for one minute. During
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this one minute delay you can abort the shutdown by typing sudo shutdown -c
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.TP
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\fB\-\-sync\fR=\fINUM\fR
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Specify how often nwipe performs an fdatasync() during cached I/O mode.
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The value refers to the number of *device hardware blocks* (commonly 512 or
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4096 bytes) written before triggering a sync. Since nwipe now writes using
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large multi-megabyte buffers, this value is automatically scaled so the sync
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interval in bytes is consistent with historic behaviour.
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The default value (100000) results in a sync approximately every 50–400 MB,
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similar to earlier nwipe releases. This ensures timely detection of I/O errors
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while maintaining good throughput.
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This setting has no effect when using --directio, as write() returns errors
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immediately under direct I/O.
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.IP
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0 \- Perform one sync only at the end of the pass.
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Not advised; errors may only be detected after the entire wipe.
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.IP
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1 \- Sync immediately after each write.
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Extremely safe but extremely slow.
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.IP
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1000 \- Sync after the equivalent of 1000 hardware blocks.
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Useful for testing or more aggressive error detection.
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.TP
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\fB\-\-cachedio\fR
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Use buffered I/O with large write buffers (page cache enabled). This is the
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default on most systems and generally gives the best performance for
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rotational disks.
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.TP
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\fB\-\-directio\fR
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Use direct I/O with large write buffers. This opens devices with
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.BR O_DIRECT
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to bypass the page cache. It can be useful when running multiple wipes in
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parallel or when you do not want to pollute the system page cache. On some
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devices this may be slower than cached I/O.
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.TP
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\fB\-\-io\-mode\fR=\fIMODE\fR
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Select the I/O mode explicitly. \fIMODE\fR can be:
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.IP
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\fBauto\fR \- (default) automatically choose the best supported mode for
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the device and kernel.
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.IP
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\fBcached\fR \- force buffered I/O.
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.IP
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\fBdirect\fR \- force direct I/O (\fBO_DIRECT\fR).
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.IP
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Large I/O buffers are used in all modes to maximise throughput.
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.TP
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\fB\-\-noblank\fR
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Do not perform the final blanking pass after the wipe (default is to blank,
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except when the method is RCMP TSSIT OPS\-II).
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.TP
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\fB\-\-nowait\fR
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Do not wait for a key before exiting (default is to wait).
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.TP
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\fB\-\-nosignals\fR
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Do not allow signals to interrupt a wipe (default is to allow).
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.TP
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\fB\-\-nousb\fR
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Do not show or wipe any USB devices, whether in GUI, --nogui or autonuke
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mode. (default is to allow USB devices to be shown and wiped).
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.TP
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\fB\-\-nogui\fR
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Do not show the GUI interface. Can only be used with the autonuke option.
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Nowait option is automatically invoked with the nogui option.
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SIGUSR1 can be used to retrieve the current wiping statistics.
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.TP
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\fB\-\-pdftag\fR
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Enables a field on the PDF that holds a tag that identifies the host computer
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.TP
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\fB\-v\fR, \fB\-\-verbose\fR
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Log more messages, useful for debugging.
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.TP
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\fB\-\-verify\fR=\fITYPE\fR
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Whether to perform verification of erasure (default: last).
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.IP
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off \- Do not verify.
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.IP
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last \- Verify after the last pass.
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.IP
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all \- Verify every pass.
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.IP
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Please mind that HMG IS5 enhanced always verifies the last (PRNG) pass
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regardless of this option.
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.TP
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\fB\-m\fR, \fB\-\-method\fR=\fIMETHOD\fR
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The wiping method (default: prng).
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.IP
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dod522022m / dod \- 7 pass DOD 5220.22\-M method
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.IP
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dodshort / dod3pass \- 3 pass DOD method
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.IP
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gutmann \- Peter Gutmann's algorithm
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.IP
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ops2 \- RCMP TSSIT OPS\-II
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.IP
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random / prng / stream \- PRNG Stream
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.IP
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zero / quick \- Overwrite with zeros (0x00)
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.IP
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one \- Overwrite with ones (0xFF)
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.IP
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verify_zero \- Verifies disk is zero (0x00) filled
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.IP
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verify_one \- Verifies disk is one (0xFF) filled
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.IP
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is5enh \- HMG IS5 enhanced
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.IP
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bruce7 \- Schneier Bruce 7-pass mixed pattern
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.IP
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bmb \- Chinese BMB21-2019 State Secrets Bureau standard.
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This method overwrites the device with ones (0xFF),
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then zeros (0x00), followed by three passes of PRNG-
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generated random data, and finishes with a final pass
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of ones (0xFF). Designed to meet the BMB21-2019
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technical sanitization requirements.
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.TP
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\fB\-l\fR, \fB\-\-logfile\fR=\fIFILE\fR
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Filename to log to. Default is STDOUT.
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.TP
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\fB\-P\fR, \fB\-\-PDFreportpath\fR=\fIDIR\fR
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Directory to write the PDF nwipe reports/certificates to.
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Defaults to ".".
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If \fIDIR\fR is set to \fInoPDF\fR no report PDF files are written.
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.TP
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\fB\-p\fR, \fB\-\-prng\fR=\fIMETHOD\fR
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The PRNG option (default: aes_ctr_prng).
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(mersenne|twister|isaac|isaac64|add_lagg_fibonacci_prng|xoroshiro256_prng|aes_ctr_prng)
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.IP
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\fBaes_ctr_prng\fR uses the Linux kernel AF_ALG interface to AES\-CTR as a
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cryptographically strong stream generator. It is seeded via
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.BR getrandom (2)
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and requires kernel crypto support for AES\-CTR.
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.TP
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\fB\-q\fR, \fB\-\-quiet\fR
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Anonymize serial numbers, GUI & logs display:
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XXXXXXXX = S/N obtained & anonymized.
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???????? = S/N not available.
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.TP
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\fB\-r\fR, \fB\-\-rounds\fR=\fINUM\fR
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Number of times to wipe the device using the selected method (default: 1).
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.TP
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\fB\-e\fR, \fB\-\-exclude\fR=\fIDEVICES\fR
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Up to ten comma separated devices to be excluded, examples:
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--exclude=/dev/sdc
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--exclude=/dev/sdc,/dev/sdd
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--exclude=/dev/sdc,/dev/sdd,/dev/mapper/cryptswap1
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--dev/disk/by-path/pci-0000:00:17.0-ata-1
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.SH BUGS
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Please see the GitHub site for the latest list:
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(https://github.com/martijnvanbrummelen/nwipe/issues)
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.SH AUTHOR
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nwipe is developed by Martijn van Brummelen <github@brumit.nl>.
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.SH "SEE ALSO"
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.BR shred (1),
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.BR dwipe (1),
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.BR dd (1),
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.BR dcfldd (1),
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.BR dc3dd (1)
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