c = Archive.
z = Use GZip format to backup. GZip is fast but it generates a larger file size than other compression tools.
p = Preserve permission so that when you restore the backup you will not encounter a permission problem.
v = Show details during backup. Omit -v if you don't want to see verbose output.
f = Specify where to store the tar files. Here we save the backup file to backup directory under user John's home directory and name it Backup.tar.gz.
/ = The Linux root file system.

Exclusions:

sudo /usr/bin/tar --exclude-from=/home/$USER/.tar_exclude.txt -czpvf /home/$USER/backup/Backup.tar.gz /

tar_exclude.txt

            /home/$USER/backup/*
            /tmp/*
            /proc/*
            /dev/*
            /sys/*
            /run/*
            /var/tmp/*
            /var/run/*
            /var/lock/*
            /usr/portage/*
            /usr/src/*

Timestamp Backups:

sudo /usr/bin/tar --exclude-from=/home/$USER/.tar_exclude.txt -czpvf /home/$USER/backup/Backup-$(date +%F-%H-%M).tar.gz /

Script:

#!bin/sh
tarfile=/home/$USER/backup/linux_backup-$(date +%F-%H-%M).tar.xz
sudo /usr/bin/tar --exclude-from=/home/$USER/exclude.txt -cJpvf $ /

Erasing files & Devices:

`dd`

dd if=/dev/zero of=/dev/sdX bs=1M &

if = Input File.
of = Output File.
bs = R/W size in bytes. (Default = 512 bytes.)

shred

shred --iterations=35 --verbose --zero --remove {FILE}

iterations = number of times to pass over the drive.
zero = Overwrite with zeroes
remove = Overwrite and remove.

Recovery

Foremost

sudo foremost -a -T -t jpg,bmp,gif,png,avi,mpg -i /dev/sdc

-a Enables all write headers -- pushes corrupt files (Usually Windows/NTFS).
-d Indirect block detection (Used for *nix systems.)
-T Time Stamps the dirs (Prevents overwriting subsequent runs of Foremost.)
-t Specify the filetype(s) for recovery.
-i Input (The path to the target device. i.e. /dev/sdX)
-o Output (Defaults to Current Dir if unspecified.)

The Grimoire 📖