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Given a file path, unplug the USB device on which the file is located (the file must be on an USB device !)
You have an external USB drive or key. Apply this command (using the file path of anything on your device) and it will simulate the unplug of this device. If you just want the port, just type : echo $(sudo lshw -businfo | grep -B 1 -m 1 $(df "/path/to/file" | tail -1 | awk '{print $1}' | cut -c 6-8) | head -n 1 | awk '{print $1}' | cut -c 5- | tr ":" "-")

Capture data in ASCII. 1500 bytes
Sniffing traffic on port 80 only the first 1500 bytes

Kill all processes that listen to ports begin with 50 (50, 50x, 50xxx,...)
Run netstat as root (via sudo) to get the ID of the process listening on the desired socket. Use awk to 1) match the entry that is the listening socket, 2) matching the exact port (bounded by leading colon and end of column), 3) remove the trailing slash and process name from the last column, and finally 4) use the system(…) command to call kill to terminate the process. Two direct commands, netstat & awk, and one forked call to kill. This does kill the specific port instead of any port that starts with 50. I consider this to be safer.

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

Pronounce an English word using Dictionary.com
This one uses dictionary.com

Send a local file via email
Another way of sending an attachment. -s : subject file : file to be sent

Watch the disk fill up
While copying a large file that may take up a good chunk of your hard drive, start the copy and run this command concurrently. It will print out the disk information every second. It's pretty handy when you have a large copy with nothing to monitor the progress.

journalctl -f
a tail -f variant of systemd journal. Follow the most recent updates or if events are appended to the journal

Show webcam output
Show the webcam output with mplayer.

Prepend a text to a file.
Using the sed -i (inline), you can replace the beginning of the first line of a file without redirecting the output to a temporary location.


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