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Display which distro is installed
Works on nearly all linux distros

Calculate the mean or average of a single column of numbers in a text file
single-column-numbers.txt is a text file with 22658 rows (numbers) in a single column. Each number can range from 0 to 134298679.533591 and the dot is for the decimals. This is done with perl because awk can't sum such high numbers.

Get ethX mac addresses
I much prefer using /sbin/ip over /sbin/ifconfig for most everything. I find the interface and output to be much more consistent and it has many abilities that ifconfig, route, etc. do not. To get the mac address for only one interface, add 'show dev [interface]' to the 'ip link' part of the command: ip link show dev eth0 | grep 'link/ether' | awk '{print $2}' . Also, both this command and the ifconfig one do not require root access to run, so the sudo is not necessary.

Show all configured ipv4
Short list of all ip. Shows even the newly supported multiple ip address on the same interface (see eth1). For ipv6 use -6

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

parse and format IP:port currently in listen state without net tools
Useful for containers and environments where you need to know if a port is currently in listen mode but you have not easy way or privileges to install net-tools like netstat or ss. "0A" is the code for listen state. The IP hex is reverse order and all in hex format.

get the full description of a randomly selected package from the list of installed packages on a debian system
I put this command on my ~/.bashrc in order to learn something new about installed packages on my Debian/Ubuntu system each time I open a new terminal

Recursive Ownership Change
Changing files ownership in a directory recursivley from a user to another

Blink Caps Lock on HDD activity
Some computers these days don't have an HDD activity light, but they still have a useless caps-lock, so why not re-purpose that light to show HDD activity? Requires setleds and dstat and probably needs to run as root.

Reclaim standard in from the tty for a script that is in a pipeline
This will grab the controlling tty regardless of what STDOUT and STDERR are doing.


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