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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" }

Simple XML tag extract with sed
Limited, but useful construct to extract text embedded in XML tags. This will only work if bar is all on one line. If nobody posts an alternative for the multiline sed version, I'll figure it out later...

Output entire line once per unique value of the first column
Removes duplicates in the specified field/column while outputting entire lines. An elegant command for processing tab (or otherwise) delimited data.

copy ACL of one file to another using getfacl and setfacl

Find default gateway (proper at ppp connections too)

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"

kill ip connection
needed; apt-get install tcpkill

Auto Get Missing Launchpad Keys
You can choose these mirror servers to get gpg keys, if the official one ever goes offline keyserver.ubuntu.com pool.sks-keyservers.net subkeys.pgp.net pgp.mit.edu keys.nayr.net keys.gnupg.net wwwkeys.en.pgp.net #(replace with your country code fr, en, de,etc)

list processes with established tcp connections (without netstat)
Uses lsof to list open network connections (file descriptors), grepping for only those in an established state

Runs previous command replacing foo by bar every time that foo appears
To replace foo by bar, but not execute, do ^foo^bar^:p To replace all foo by bar, but not execute, do ^foo^bar^:&:p


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