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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"

quickly backup or copy a file with bash
This inserts timestamp instead of .bak extension.

Display a Lissajous curve in text
Use Ruby's standard Curses module to display a Lissajous curve in the console. Replace the "0.2" with different numbers for different curves.

Run a bash script in debug mode, show output and save it on a file

Quickly find a count of how many times invalid users have attempted to access your system

Get AWS temporary credentials ready to export based on a MFA virtual appliance
You might want to secure your AWS operations requiring to use a MFA token. But then to use API or tools, you need to pass credentials generated with a MFA token. This commands asks you for the MFA code and retrieves these credentials using AWS Cli. To print the exports, you can use: `awk '{ print "export AWS_ACCESS_KEY_ID=\"" $1 "\"\n" "export AWS_SECRET_ACCESS_KEY=\"" $2 "\"\n" "export AWS_SESSION_TOKEN=\"" $3 "\"" }'` You must adapt the command line to include: * $MFA_IDis ARN of the virtual MFA or serial number of the physical one * TTL for the credentials

Find out how old a web page is
I used to use the Firefox "View page info" feature a lot to determine how stale the web page I was looking at was. Now that I use mostly Chrome I miss that feature, so here is a command line alternative using wget. The -S says to display the server response, the --spider says to not download any files/pages, just fetch the header. The output goes to stderr, so to grep it you use 2>&1 to combine the stderr stream with stdout, the pipe that to grep for Last-Modified. You can use curl instead if you have it installed, like this: $ curl --head -s http://osswin.sourceforge.net | grep Mod

NICs, IPs, and Mac
Needed to get the Mac of various devices on a solaris box, but didn't have root. This command used awk to display the Network device, the IP, and the MAC a line at a time.

Count all conections estabilished on gateway

Show all the available information about your current distribution, package management and base
Just run this command and it will printout all the info available about your current distribution and package management system.


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