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Do one ping to a URL, I use this in a MRTG gauge graph to monitor connectivity

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Calculate days on which Friday the 13th occurs (inspired from the work of the user justsomeguy)
Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale.

check open ports without netstat or lsof

Clone all repos from a user with lynx
https://wuseman.github.io/wcloner/

To print a specific line from a file
Just one character longer than the sed version ('FNR==5' versus -n 5p). On my system, without using "exit" or "q", the awk version is over four times faster on a ~900K file using the following timing comparison: $ testfile="testfile"; for cmd in "awk 'FNR==20'" "sed -n '20p'"; do echo; echo $cmd; eval "$cmd $testfile"; for i in {1..3}; do time for j in {1..100}; do eval "$cmd $testfile" >/dev/null; done; done; done Adding "exit" or "q" made the difference between awk and sed negligible and produced a four-fold improvement over the awk timing without the "exit". For long files, an exit can speed things up: $ awk 'FNR==5{print;exit}'

Print one . instead of each line
If you're running a command with a lot of output, this serves as a simple progress indicator. This avoids the need to use `/dev/null` for silencing. It works for any command that outputs lines, updates live (`fflush` avoids buffering), and is simple to understand.

mplayer webcam window for screencasts
When recording screencast some people like to have the image from their webcam, so the can show something, that can't be seen on the desktop. So starting mplayer with these parameters you will have a window with no frames, borders whatsoever, and selecting the window a hitting the "F" key you will bring it in fullscreen. if you want to position the frame somewhere else, you could play with the --geomeptry option where 100%:100% mean bottom right corner. The HEIGHT and WIDTH can't be changed as you like, since the most webcams support specified dimensions, so you would have to play with it to see what is supported

Command line calculator
This function defines a command line calculator that handles everything pythons math module can handle, e.g. trigonometric functions, sqrt, log, erf, ... (see http://docs.python.org/library/math.html). It even knows about the constants pi and e.

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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