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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"

Set all CPU cores' CPU frequency scaling governor to maximum performance

Test for Weak SSL Ciphers
...if you get a certificate back, the server is accepting weak SSL ciphers

Get your external IP address
Yeah I know it's been up here a million times, but this service is a really clean and nice one. Nothing but your IP address on it. Actually I was to write something like this, and noticed this on appspot... ;)

Backup a file with a date-time stamp
Appends the input file with the date format YYYY-MM-DD.bak. Also runs silently if you remove the -v on the cp at the end of the function.

Have a smile
Outputs utf-8 smileys

Simplest port scanner
Very handy way to perform a host scan if you don't have nmap,ncat,nc ...or other tools installed locally. When executing a command on a /dev/tcp/$host/$port pseudo-device file, Bash opens a TCP connection to the associated socket and UDP connection when using /dev/udp/$host/$port.A simlpe way to get servers banner is to run this command "cat < /dev/tcp/localhost/25" , here you will get mail server's banner. NOTE: Bash, as packaged for Debian, does not support using the /dev/tcp and /dev/udp pseudo-device it's not enabled by default Because bash in Debian is compiled with ?disable-net-redirections.

Check if the Debian package was used since its installation/upgrade.
This script compares the modification date of /var/lib/dpkg/info/${package}.list and all the files mentioned there. It could be wrong on noatime partitions. Here is non-oneliner: #!/bin/sh package=$1; list=/var/lib/dpkg/info/${package}.list; inst=$(stat "$list" -c %X); cat $list | ( while read file; do if [ -f "$file" ]; then acc=$(stat "$file" -c %X); if [ $inst -lt $acc ]; then echo used $file exit 0 fi; fi; done exit 1 )

Listen to a song from youtube with youtube-dl and mpv
Explanation Firstly the function checks if user gave it any input, and notifies the user if they failed to do so. If user has inputed a search string, the function will call upon youtube-dl to find url of the audio of the first matching youtube video and play that with mpv. Call function by wrapping search string in quotes: listen-to-yt "sultans of swing" You have to paste the line in your .zshrc and source .zshrc for it to work. Limitations The dependancies are youtube-dl and mpv. this oneliner is stolen from http://www.bashoneliners.com/oneliners/302/

Check disk I/O


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