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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"

Print all the lines between 10 and 20 of a file
Subtly different to the -n+p method... and probably wrong in so many ways....... But it's shorter. Just.

Safely remove old unused kernels in Ubuntu/Debian
Removes piling kernels from /boot, save the current one. This command DOES NOT remove the 'linux-image-generic' package, so you'll continue getting kernel updates

Advanced python tracing
Trace python statement execution and syscalls invoked during that simultaneously

Calculate files' size

Touch a file using a timestamp embedded in the file name.
tstouch takes two arguments: a filename containing a timestamp, and an extended regular expression with the parenthesized section matching a timestamp of the form YYYYMMDDhhmm or YYYYMMDDhhmm.ss. It then touches the file with that timestamp.

Randomize lines in a file
Works in sort (GNU coreutils) 7.4, don't know when it was implemented but sometime the last 6 years.

Instead of writing a multiline if/then/else/fi construct you can do that by one line
instead of writing: if [[ "$1" == "$2" ]]; then echo "$1 is equal $2" else echo "$1 differs from $2" fi do write: [[ "$1" == "$2" ]] && echo "$1 is equal $2" || echo "$1 differs from $2"

Extract audio from Mythtv recording to Rockbox iPod using ffmpeg
There are some pretty good live performances on late night TV. With Mythtv I record David Letterman, Jimmy Fallon, and Conan nightly all in HD from over the air broadcasts. If I find a live performance I like I copy it to my Rockboxed iPod using this command. The Rockbox firmware knows how to downmix 5.1 audio. The command above extracts the audio from the video starting at 58 minutes and 15 seconds. It ends at the end of the file since this was the last performance of the recording. The command creates an ac3 file. I copy the ac3 file to my Rockbox iPod and rock on.

Traceroute w/TCP to get through firewalls.
man tcptraceroute


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