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Randomize lines in a file
shuf is in the coreutils package

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

Update dyndns.org with your external IP.
This is great if you are behind a router that does not support dynamic dns updates! Example: AT&T u-verse gateway... Put this in a script and run it as a cron job.

list files recursively by size

check open ports without netstat or lsof

Start a SOCKS proxy to avoid a restrictive firewall
You may go to Internet by means of your home ssh server. You must configure your local proxy to send traffic through the proxy. Many programs allows that: firefox, pidgin, skype, gnome, etc. Your home ssh server must listen in any of the ports permitted by your enterprise firewall. That usually includes 80 and 443.

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"

Query ip pools based on successive netnames via whois
Useful if you f.i. want to block/allow all connections from a certain provider which uses successive netnames for his ip blocks. In this example I used the german Deutsche Telekom which has DTAG-DIAL followed by a number as netname for the dial in pools. There are - as always ;) - different ways to do this. If you have seq available you can use $ net=DTAG-DIAL ; for i in `seq 1 30`; do whois -h whois.ripe.net $net$i | grep '^inetnum:' | sed "s;^.*:;$net$i;" ; done or without seq you can use bash brace expansion $ net=DTAG-DIAL ; for i in {1..30}; do whois -h whois.ripe.net $net$i | grep '^inetnum:' | sed "s;^.*:;$net$i;" ; done or if you like while better than for use something like $ net=DTAG-DIAL ; i=1 ; while true ; do whois -h whois.ripe.net $net$i | grep '^inetnum:' | sed "s;^.*:;$net$i;" ; test $i = 30 && break ; i=$(expr $i + 1) ; done and so on.

Resume aborted scp file transfers
Put it into your sh startup script (I use alias scpresume='rsync --partial --progress --rsh=ssh' in bash). When a file transfer via scp has aborted, just use scpresume instead of scp and rsync will copy only the parts of the file that haven't yet been transmitted.

check open ports without netstat or lsof


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