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Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

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"

Get your external IP address if your machine has a DNS entry
Using DynDNS or a similar service not only allows access to your home machine from outside without needing to know what IP the ISP has assigned to it but it also comes in handy if you want to know your external IP address. The only purpose of the sed command is to remove the leading "host.na.me has address " part from the output. If you don't need to discard it you can simply use $ host $HOSTNAME

copy public key

Kill all processes belonging to a user
This is a 'killall' command equivalent where it is not available. Prior to executing it, set the environment variable USERNAME to the username, whose processes you want to kill or replace the username with the $USERNAME on the command above. Side effect: If any processes from other users, are running with a parameter of $USERNAME, they will be killed as well (assuming you are running this as root user) [-9] in square brackets at the end of the command is optional and strongly suggested to be your last resort. I do not like to use it as the killed process leaves a lot of mess behind.

Create date-based tgz of current dir, runs in the background, very very cool
This is freaking sweet!!! Here is the full alias, (I didn't want to cause display problems on commandlinefu.com's homepage): $ alias tarred='( ( D=`builtin pwd`; F=$(date +$HOME/`sed "s,[/ ],#,g"

RTFM function
RTFMFTW.

Get your external IP address ( 10 characters long )
Shortest url to a external IP-service, 10 characters.

See system users

list files recursively by size


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