Commands by pjsb (1)

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Compare / diff two images
Outputs the number of different pixels. 2 params to increase tolerance: * thumbnails size * fuzz, the color distance tolerance See http://en.positon.org/post/Compare-/-diff-between-two-images for more details.

compare two Microsoft Word documents
http://meld.sourceforge.net/ http://www.winfield.demon.nl/

pngcrush all .png files in the directory
Find all pngs in directory structure and pngcrush them, none destructive. You can just remove the "{}.crush" part if you want destructive.

Print a cron formatted time for 2 minutes in the future (for crontab testing)
Another function to stick into your .bashrc This spits out the time two minutes in the future, but already formatted for pasting into your crontab file for testing without any thought required on your part. Frequently things don't work the way you expect inside a crontab job, and you probably want to find out now that your $PATH is completely different inside of cron or other global variables aren't defined. So this will generate a date you can use for testing now, and then later you can change it to run at 5:37 am on a Sunday evening.

C function manual

Port scan a range of hosts with Netcat.
Simple one-liner for scanning a range of hosts, you can also scan a range of ports with Netcat by ex.: nc -v -n -z -w 1 192.168.0.1 21-443 Useful when Nmap is not available:) Range declaration like X..X "for i in {21..29}" is only works with bash 3.0+

Randomize lines in a file
Works in sort (GNU coreutils) 7.4, don't know when it was implemented but sometime the last 6 years.

append empty line after every line in file.txt

Merge various PDF files

GZip all files in a directory separately
It gzip each file in a directory separately


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