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Duplicate several drives concurrently
If you have some drive imaging to do, you can boot into any liveCD and use a commodity machine. The drives will be written in parallel. To improve efficiency, specify a larger block size in dd: $dd if=/dev/sda bs=64k | tee >(dd of=/dev/sdb bs=64k) | dd of=/dev/sdc bs=64k To image more drives , insert them as additional arguments to tee: $dd if=/dev/sda | tee >(dd of=/dev/sdb) >(dd of=/dev/sdc) >(dd of=/dev/sdd) | dd of=/dev/sde

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

The proper way to read kernel messages in realtime.

Replace duplicate files by hardlinks

ping as traceroute
This command uses ping to get the routers' IP addresses to the destination host as traceroute does. If you know what I mean..

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" }

Print interface that is up and running

Calculate N!

Remove CR LF from a text file
Remove CR LF (CRLF) from a text file. use man:tr to get more info about removing other characters from a file. and even character to character replacements.

vi show line numbers
you don't have to spell out numbers, you can just use nu


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