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Remove duplicate rows of an un-sorted file based on a single column
The command (above) will remove any duplicate rows based on the FIRST column of data in an un-sorted file. The '$1' represents a positional parameter. You can change both instances of '$1' in the command to remove duplicates based on a different column, for instance, the third: $ awk '{ if ($3 in stored_lines) x=1; else print; stored_lines[$3]=1 }' infile.txt > outfile.txt Or you can change it to '$0' to base the removal on the whole row: $ awk '{ if ($0 in stored_lines) x=1; else print; stored_lines[$0]=1 }' infile.txt > outfile.txt ** Note: I wouldn't use this on a MASSIVE file, unless you're RAM-rich ;) **

Simple Video Surveillance by email
This takes a picture (with the web cam) every 5 minutes, and send the picture to your e-mail. Some systems support mail -a "References: " so that all video surveillance emails are grouped in a single email thread. To keep your inbox clean, it is still possible to filter and move to trash video surveillance emails (and restore these emails only if you really get robbed!) For instance with Gmail, emails sent to me+trash@gmail.com can be filtered with "Matches: DeliveredTo:me+trash@gmail.com"

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get header and footer of file for use with scalpel file carving
file carving helps if you know where the file you are looking for starts and ends. It's also an easy way to get data and catalog them for future use with forensic tools like scalpel.

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"

Record audio and video from webcam using ffmpeg
Record from a webcam, audio using ALSA encoded as MP3, video as MPEG-4.

Make a DVD ISO Image from a VIDEO_TS folder on MacOSX
/path/ is the root folder of the DVD, not the VIDEO_TS folder.

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

a function to find the fastest DNS server
http://public-dns.info gives a list of online dns servers. you need to change the country in url (br in this url) with your country code. this command need some time to ping all IP in list.

floating point operations in shell scripts
allows you to use floating point operations in shell scripts


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