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Ping Twitter to check if you can connect
Returns a JSON object, by connecting to the 'test' endpoint of the Twitter API. Simplest way to check if you can connect to Twitter. Output also available in XML, use '/help/test.xml' for that

which process has a port open

bash-quine
this command prints itself out. it doesn't need to be stored in a file and it isn't as easy as $ echo $BASH_COMMAND for information on quines see http://en.wikipedia.org/wiki/Quine_(computing)

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Watch Network Service Activity in Real-time

Monitor all DNS queries made by Firefox

Block an IP address from connecting to a server
This appends (-A) a new rule to the INPUT chain, which specifies to drop all packets from a source (-s) IP address.

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"

Simplified video file renaming
I used this when I had a directory of movies from a camera. I wanted to watch a little of each movie, then rename it depending on what was in the movie. This did the trick for me.


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