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display a one-liner of current nagios exit statuses. great with netcat/irccat

Find running binary executables that were not installed using dpkg
This helped me find a botnet that had made into my system. Of course, this is not a foolproof or guarantied way to find all of them or even most of them. But it helped me find it.

start vim in diff mode
vim will open both files side by side and show colored diffs

Write comments to your history.
A null operation with the name 'comment', allowing comments to be written to HISTFILE. Prepending '#' to a command will *not* write the command to the history file, although it will be available for the current session, thus '#' is not useful for keeping track of comments past the current session.

IP addresses connected to port 80
IP addresses and number of connections connected to port 80.

ROT13 using the tr command

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" }

Go up multiple levels of directories quickly and easily.
Change to your taste. Much quicker than having to add 'cd' every time. Add it to your .bashrc or .bash_profile.

recursive search and replace old with new string, inside files
recursively traverse the directory structure from . down, look for string "oldstring" in all files, and replace it with "newstring", wherever found also: $ grep -rl oldstring . |xargs perl -pi~ -e 's/oldstring/newstring'

Get technical and tag information about a video or audio file
MediaInfo supplies technical and tag information about a video or audio file. (sudo apt install mediainfo)


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