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check open ports without netstat or lsof

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"

Capture FTP Credentials and Commands

Find usb device in realtime
Using this command you can track a moment when usb device was attached.

Define shell variable HISTIGNORE so that comments (lines starting with #) appear in shell history
I was surprised to find that with RedHat bash, I could not find any comment lines (begining with #) in my bash shell history. Surprised because in Mageia Linux this works. It turns out that RedHat's bash will keep comment lines if in my .bashrc, I define: export HISTIGNORE=' cd "`*: PROMPT_COMMAND=?*?' Why have comment lines in shell history? It's a handy and convenient way to make proto-commands (to be completed later) and for storing brief text data that is searchable in shell history.

Run a command as root, with a delay
$ sleep 1h ; sudo command or $ sudo sleep 1h ; sudo command won't work, because by the time the delay is up, sudo will want your password again.

See where a shortened url takes you before click

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" }

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" }

Check wireless link quality with dialog box
The variable WIRELESSINTERFACE indicates your wireless interface


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