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Keep one instance of an irc chat client in a screen session
This command attempts to attach to existing irssi session, if one exists, otherwise creates one. I use "irc" because I use different irc clients depending on what system I am working on. Consistency is queen.

Delete C style comments using vim

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"

monitor memory usage

Make vim open in tabs by default (save to .profile)
I always add this to my .profile rc so I can do things like: "vim *.c" and the files are opened in tabs.

Check if a machine is online
PING parameters c 1 limits to 1 pinging attempt q makes the command quiet (or silent mode) /dev/null 2>&1 is to remove the display && echo ONLINE is executed if previous command is successful (return value 0) || echo OFFLINE is executed otherwise (return value of 1 if unreachable or 2 if you're offline yourself). I personally use this command as an alias with a predefined machine name but there are at least 2 improvements that may be done. Asking for the machine name or IP Escaping the output so that it displays ONLINE in green and OFFLINE in red (for instance).

Run 10 curl commands in parallel via xargs (v2, faster then v1)

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"

Use AWS CLI and JQ to get a list of instances sorted by launch time
Use the AWS CLI tools to generate a list instances, then pipe them to JQ to show only their launch time and instance id. Finally use sort to bring them out in runtime order. Find all those instances you launched months ago and have forgotten about.

Reducing image size
Adding the exclamation mark to the image geometry ignores the original aspect ratio. More info about image geometry: http://www.imagemagick.org/script/command-line-processing.php#geometry


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