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launch bash without using any letters
ry4an@four:~$ echo $SHLVL 1 ry4an@four:~$ ${0/-/} ry4an@four:~$ echo $SHLVL 2

Anti DDOS
Takes IP from web logs and pipes to iptables, use grep to white list IPs.. use if a particular file is getting requested by many different addresses. Sure, its already down pipe and you bandwidth may suffer but that isnt the concern. This one liner saved me from all the traffic hitting the server a second time, reconfigure your system so your system will work like blog-post-1.php or the similar so legitimate users can continue working while the botnet kills itself.

Tells you where a command is in your $PATH, but also wether it's a link and to what.
You may also use the $(which foo) variant instead of backticks. I personnaly have an alias ll='ls -l'.

split a multi-page PDF into separate files
Have to do this once per output file, because if device is 'pdfwrite', even if 'gs' sees '%d' in the OutputFile it still only creates one single output file. Embed it into a simple shell script if you want to split a document out into one file for every page.

Touch a file using a timestamp embedded in the file name.
tstouch takes two arguments: a filename containing a timestamp, and an extended regular expression with the parenthesized section matching a timestamp of the form YYYYMMDDhhmm or YYYYMMDDhhmm.ss. It then touches the file with that timestamp.

Create a new file

Find writable files
Have a grudge against someone on your network? Do a "find -writable" in their directory and see what you can vandalize! But seriously, this is really useful to check the files in your own home directory to make sure they can't inadvertently be changed by someone else's wayward script.

remap Caps_Lock to Escape

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Detect illegal access to kernel space, potentially useful for Meltdown detection
Based on capsule8 agent examples, not rigorously tested


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