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Display the standard deviation of a column of numbers with awk
This will calculate a running standard deviation in one pass and should never have the possibility for overflow that can happen with other implementations. I suppose there is a potential for underflow in the corner case where the deltas are small or the values themselves are small.

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"

Matrix Style
I like the fact the Patola's version uses only ones and zeros, but I also like the sparse output of the other versions. This one combines both of those features and eliminates some unnecessary cruft. You can vary the sparseness by changing "$(($RANDOM % 5))" to another number. The number in this term "$(($RANDOM % 4))" controls how frequently the numbers are output bold.

Find the package that installed a command

unbuffered python output
You have a python script that slowly prints output, you want to pipe the output to grep or tee, and you are impatient and want to watch the results right away. Rather than modify your script (making it slightly less efficient), use the -u option to have the output unbuffered.

prints line numbers

recursive search and replace old with new string, inside files
Using -Z with grep and -0 with xargs handles file names with spaces and special characters.

Remove a range of lines from a file

List bash functions defined in .bash_profile or .bashrc
typeset command gives to stdout all the functions defined in a bash session, -f and -F switches are for: all functions names with body (-f) and all functions names only (-F).

Find the most recent snapshot for an AWS EBS volume
Uses the python-based AWS CLI (https://aws.amazon.com/cli/) and the JSON query tool, JQ (https://stedolan.github.io/jq/)


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