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Use socat to emulate an SMTP mail SERVER
Lots of scripts show you how to use socat to send an email to an SMTP server; this command actually emulates an SMTP server! It assumes the client is only sending to one recipient, and it's not at all smart, but it'll capture the email into a log file and the client will stop retrying. I used this to diagnose what emails were being sent by cron and subsequently discarded, but you can use it for all sorts of things.

Search big files with long lines
This is a handy way to circumvent the "Maximum line length of 2048 exceeded" grep error. Once you have run the above command (or put it in your .bashrc), files can be searched using: $ lgrep search-string /file/to/search

Sort files by size

Merges given files line by line
In the above example all files have 4 lines. In "file1" consecutive lines are: "num, 1, 2, 3", in "file2": "name, Jack, Jim, Frank" and in "file3": "scores, 1300, 1100, 980". This one liner can save considerate ammount of time when you're trying to process serious portions of data. "-d" option allows one to set series of characters to be used as separators between data originating from given files.

print all except first collumn

Network Folder Copy with Monitoring ( tar + nc + pv )
Transfer tar stream thru nc with pv montoiring taken from: http://www.catonmat.net/blog/unix-utilities-pipe-viewer/

sorting file contents into individual files with awk
This command will sort the contents of FILENAME by redirecting the output to individual .txt files in which 3rd column will be used for sorting. If FILENAME contents are as follows: foo foo A foo bar bar B bar lorem ipsum A lorem Then two files called A.txt and B.txt will be created and their contents will be: A.txt foo foo A foo lorem ipsum A lorem and B.txt will be bar bar B bar

show each new entry in system messages as a popup
It willl popup a message for each new entry in /var/log/messages found on the notify-send howto page on ubuntuforums.org. Posted here only because it is one of the favourites of mine.

Print github url for the current url
Works for repos cloned via ssh or https.

create a simple version of ls with extended output
create a short alias for 'ls' with multi-column (-C), file type syntax additions (slashes after directories, @ for symlinks, etc... (-F), long format (-l), including hidden directories (all ./, ../, .svn, etc) (-a), show file-system blocks actually in use (-s), human readable file sizes (-h)

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