find all computer connected to my host through TCP connection. Show Sample Output
This command takes the output of the 'last' command, removes empty lines, gets just the first field ($USERNAME), sort the $USERNAMES in reverse order and then gives a summary count of unique matches. Show Sample Output
This command lets you see and scroll through all of the strings that are stored in the RAM at any given time. Press space bar to scroll through to see more pages (or use the arrow keys etc).
Sometimes if you don't save that file that you were working on or want to get back something you closed it can be found floating around in here!
The awk command only shows lines that are longer than 20 characters (to avoid seeing lots of junk that probably isn't "human readable").
If you want to dump the whole thing to a file replace the final '| less' with '> memorydump'. This is great for searching through many times (and with the added bonus that it doesn't overwrite any memory...).
Here's a neat example to show up conversations that were had in pidgin (will probably work after it has been closed)...
sudo cat /proc/kcore | strings | grep '([0-9]\{2\}:[0-9]\{2\}:[0-9]\{2\})'
(depending on sudo settings it might be best to run
sudo su
first to get to a # prompt)
Just a simple way without the need of additional tools. Of course, replace eth0 with your IF. Show Sample Output
parse "lsmod" output to "dot" format and pass it to "display". Without perl!
Another combination of seq and awk. Not very efficient, but sufficiently quick. Show Sample Output
Here is a command line to run on your server if you think your server is under attack. It prints our a list of open connections to your server and sorts them by amount.
BSD Version:
netstat -na |awk '{print $5}' |cut -d "." -f1,2,3,4 |sort |uniq -c |sort -nr
Show Sample Output
Plot your most used commands with gnuplot.
Self-referential use of wget. Show Sample Output
A variation of a script I found on this site and then slimmed down to just use awk. It displays all users who have attempted to login to the box and failed using SSH. Pipe it to the sort command to see which usernames have the most failed logins. Show Sample Output
Purge all configuration files of removed packages Show Sample Output
i'm using gawk, you may get varying mileage with other varieties. You might want to change the / after du to say, /home/ or /var or something, otherwise this command might take quite some time to complete. Sorry it's so obsfucated, I had to turn a script into a one-liner under 255 characters for commandlinefu. Note: the bar ratio is relative, so the highest ratio of the total disk, "anchors" the rest of the graph. EDIT: the math was slightly wrong, fixed it. Also, made it compliant with older versions of df. Show Sample Output
Rather than chain a string of greps together and pipe them to awk, use awk to do all the work. In the above example, a string would be output to stdout if it matched pattern1 AND pattern2, but NOT pattern3.
usefull in case of abuser/DoS attacks. Show Sample Output
simple function , floating point number is supported.
Proper screencast with audio using ffmpeg and x264, as per http://verb3k.wordpress.com/2010/01/26/how-to-do-proper-screencasts-on-linux/
Awk replaces every instance of foo with bar in the 5th column only.
..not guaranteed to always be accurate but fun to see how old you Linux installation is based on the root partitions file system creation date. Show Sample Output
A more efficient way, with reversed order to put the focus in the big ones. Show Sample Output
using
cat WAR_AND_PEACE_By_LeoTolstoi.txt | tr -cs "[:alnum:]" "\n"| tr "[:lower:]" "[:upper:]" | sort -S16M | uniq -c |sort -nr | cat -n | head -n 30
("sort -S1G" - Linux/GNU sort only) will also do the job but as some drawbacks (caused by space/time complexity of sorting) for bigger files...
Show Sample Output
Here's an awk alternative, for those lacking the version of cut with the --complement argument.
It identifies the parents of the Zombie processes and kill them. So the new parent of orphan Zombies will be the Init process and he is already waiting for reaping them. Be careful! It may also kill your useful processes just because they are not taking care and waiting for their children (bad parents!). Show Sample Output
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