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mean color of an image
You can get the mean value for the colours in an image. Then you can determine, in general, how dark or bright is the image and run some other actions based on that. I'll recommend to readjust the brightness of the images using +sigmoidal-contrast option of imagemagick convert command.

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

Google voice recognition "API"
The FLAC audio must be encoded at 16000Hz sampling rate (SoX is your friend). Outputs a short JSON string, the actual speech is in the hypotheses->utterance, the accuracy is stored in hypotheses->confidence (ranging from 0 to 1). Google also accepts audio in some special speex format (audio/x-speex-with-header-byte), which is much smaller in comparison with losless FLAC, but I haven't been able to encode such a sample.

ssh autocomplete
Stop tormenting the poor animal cat. See http://sial.org/howto/shell/useless-cat/. Edit: replaced $ sort | uniq by $ sort -u

Show the last 20 sessions logged on the machine
change 20 by the number of sessions you want to know (20 it's fair enough)

Get your outgoing IP address
Instead of opening your browser, googling "whatismyip"... Also useful for scripts. dig can be found in the dnsutils package.

Pretty-print user/group info for a given user

create and md5 sum of your password
create and md5 sum of your password without it showing up in your terminal or history. Afterwards we overwrite the $p variable (thx to bazzargh)

Adding Prefix to File name
Good old bracket expansion :-) For large numbers of files, "rename" will spare you the for-loop, or the find/exec...

Sort output by column
(separator = $IFS)


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