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Capture video of a linux desktop
This will grab the image from desktop, starting with the upper-left corner at x=100, y=200 with a width and height of 1024?768.

Catch a proccess from a user and strace it.
It sits there in a loop waiting for a proccess from that user to spawn. When it does it will attach strace to it

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" }

Show the last 20 sessions logged on the machine
change 20 by the number of sessions you want to know (20 it's fair enough)

Monitor dynamic changes in the dmesg log.
Other logs can be monitored similarly, e.g. $ watch "tail -15 /var/log/daemon.log"

Live stream a remote desktop over ssh using only ffmpeg
Play with the framerate option '-r' to scale back bandwidth usage. The '-s' option is the captured screan area, not the rescaled size. If you want to rescale add a second '-s' option after '-i :0'. Rescaling smaller will also decrease bandwidth.

list block devices
Shows all block devices in a tree with descruptions of what they are.

Get list of servers with a specific port open
Change the -p argument for the port number. See "man nmap" for different ways to specify address ranges.

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" }

cleanup /tmp directory
Cleans all files in /tmp that have been accessed at least 2 days ago.


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