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Run the last command as root
Same as `sudo !!`. If you do not have permission to be sudo or sudo does not installed on your system, you can use this.

Rescan partitions on a SCSI device
Used this after cloning a disk with dd to make the newly written partitions show up in /dev/

cd into the latest directory

Selecting a random file/folder of a folder
Also looks in subfolders

Migrate Server with rsync
Copies the complete root-dir of a linux server to another one, where the new harddisks formated and mountet. Very useful to migrate a root-server to another one.

make 100 directories with leading zero, 001...100, using bash3.X

Remove duplicate rows of an un-sorted file based on a single column
The command (above) will remove any duplicate rows based on the FIRST column of data in an un-sorted file. The '$1' represents a positional parameter. You can change both instances of '$1' in the command to remove duplicates based on a different column, for instance, the third: $ awk '{ if ($3 in stored_lines) x=1; else print; stored_lines[$3]=1 }' infile.txt > outfile.txt Or you can change it to '$0' to base the removal on the whole row: $ awk '{ if ($0 in stored_lines) x=1; else print; stored_lines[$0]=1 }' infile.txt > outfile.txt ** Note: I wouldn't use this on a MASSIVE file, unless you're RAM-rich ;) **

Find usb device
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him

Get your external IP address without curl
Curl is not installed by default on many common distros anymore. wget always is :) $ wget -qO- ifconfig.me/ip

Securely destroy data (including whole hard disks)
GNU shred is provided by the coreutils package on most Linux distribution (meaning, you probably have it installed already), and is capable of wiping a device to DoD standards. You can give shred any file to destroy, be it your shell history or a block device file (/dev/hdX, for IDE hard drive X, for example). Shred will overwrite the target 25 times by default, but 3 is enough to prevent most recovery, and 7 passes is enough for the US Department of Defense. Use the -n flag to specify the number of passes, and man shred for even more secure erasing fun. Note that shredding your shell history may not be terribly effective on devices with journaling filesystems, RAID copies or snapshot copies, but if you're wiping a single disk, none of that is a concern. Also, it takes quite a while :)


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