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find out how much space are occuipied by files smaller than 1024K (sic) - improved
The original didn't use -print0 which fails on weird file names eg with spaces. The original parsed the output of 'ls -l' which is always a bad idea.

Get your external IP address ( 10 characters long )
Shortest url to a external IP-service, 10 characters.

To get the CPU temperature continuously on the desktop
No need for a colon, and one less semicolon too. Also untested.

Scan all open ports without any required program

Turn white color to transparent for a series of png images
mogrify can be used like convert. The difference is that mogrify overwrites files: http://www.imagemagick.org/www/mogrify.html Of course, other source colors can be used as well.

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

save stderr only to a file
taken from http://www.unix.com/shell-programming-scripting/158311-how-tee-stderr.html " What does it mean? The redirection operator n>&m makes file descriptor n to be a copy of file descriptor m. So, whe are: - Opening a new file descriptor, 3, that is a copy of file descriptor 1, the standard output; - Making file descriptor 1 a copy of file descriptor 2, the standard error output; - Making file descriptor 2 to be a copy of file descriptor 3 (the "backup" of the standard output) in a short: we swapped the standard output and the standard error output. "

Display a block of text: multi-line grep with perl
-n reads input, line by line, in a loop sending to $_ Equivalent to while () { mycode } -e execute the following quoted string (i.e. do the following on the same line as the perl command) the elipses .. operator behaves like a range, remembering the state from line to line.

Monitoring sessions that arrive at your server

Create a QR code image in MECARD format
Add the QR code image on your webpage, business card ., etc, so people can scan it and quick add to their Contact Address Book. Tested on iPhone with QRreader.


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