Commands by KaytlynJane (0)

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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"

Check if a machine is online with better UI
I have used single packet, and in a silent mode with no display of ping stats. This is with color and UI improvement to the http://www.commandlinefu.com/commands/view/10220/check-if-a-machine-is-online. It is as per the enhancements suggested.

Host cpu performance
Measure the cpu performance: In-case if the cpu is thermal throttling then you can find it using this command. Check the first line of the output. Example: Doing md5 for 3s on 16 size blocks: 11406892 md5's in 2.98s ? #(When cpu is not throttling) Doing md5 for 3s on 16 size blocks: 110692 md5's in 2.98s ?? #(When cpu is thermal throttling) Practical use case: Once we had cooling outage in data center which caused thermal throttling in some of the worker nodes. We used this tool to prove that some servers are not performing well because of the cpu thermal throttling.

Create and play an instant keyword based playlist
It works best as part of a function, such as the following: MUSICROOT=~/Music function fplay { if [ $1 = '-v' ]; then shift 1 find -E $MUSICROOT -type f -iname "*$**" -iregex '.*\.(3g[2|p]|aac|ac3|adts|aif[c|f]?|amr|and|au|caf|m4[a|r|v]|mp[1-4|a]|mpeg[0,9]?|sd2|wav)' -print -exec afplay "{}" \; & else find -E $MUSICROOT -type f -iname "*$**" -iregex '.*\.(3g[2|p]|aac|ac3|adts|aif[c|f]?|amr|and|au|caf|m4[a|r|v]|mp[1-4|a]|mpeg[0,9]?|sd2|wav)' -exec afplay "{}" \; & fi }

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"

find out how many days since given date
You can also do this for seconds, minutes, hours, etc... Can't use dates before the epoch, though.

Unzip and untar a *.tar.gz file in one go to a specific directory
A *.tar.gz file needs to be unzipped & then untarred. Previously I might have unzipped first with $gunzip -d file.tar.gz and then untarred the result with $tar -xvf file.tar (Options are extract, verbose, file) Using the -z (decompress) option on tar avoids the use of gzip (or gunzip) first. Additionally the -C option will specify the directory to extract to.

statistics in one line
In this example, file contains five columns where first column is text. Variance is calculated for columns 2 - 5 by using perl module Statistics::Descriptive. There are many more statistical functions available in the module.

List all installed kernels on Ubuntu except current one
Lists all installed kernels minus the current one. This is useful to uninstall older kernels that take too much space on /boot partition.

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"

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