This is a quick post to show how one can issue commands to telnet session from a shell script or command line with out going into interactive mode. I use this to get stats from our memcache servers or issue a flush_all via telnet from a script/cron.

So without further delay, following command will telnet to local memcached server on port 11211 and issue one of the memcached commands, stats

(sleep .5;echo stats) | telnet localhost 11211
You may have to play with the sleep timer to get it to work for your environment but in our .5 was the sweet spot. Good luck and let me know if you have another shell command. Obviously we can do this from perl, php, python, etc but the beauty of this is that you do not need any other dependencies plus its a very short command. …

In Linux, there is no command which will rename a user account. If you make a mistake creating a user account, user changes their name or if user does not like his user name, there is no real easy way of going and making the change. Only thing I know you can do is to go through some files and rename user manually. Let us say that we have a user who is named joe and we want to rename him to john.

Note: you must be logged in as root to do following.

vi /etc/passwd
find joe and change it to john, save/exit

vi /etc/group
find joe and change it to john, save/exit

vi /etc/shadow
find joe and change it to john. This file is read only and you have to force overwrite it. In vi it is :w! once saved, quit.

cd /home
mv joe john

And that should do the trick.

[Edited] Right after I posted this post, I was contacted and was told to look at utility called usermod. Read …

Buddy of mine asked me a question over chat today: “how do I show my machines’ IP at login prompt with out logging in?” He is referring to his Virtual Machine in this case. He does not want to have to log in to the server to see what ip it has (since its on dhcp) for him to ssh in or hit it from the browser. I could have answered him with a simple how to but what is the fun in that? So I decided to give some background on how login prompts are done and show what can be done.

When Linux server boots up, it calls a program called mingetty. This program creates that infamous login prompt as show in a screenshot:

You can see how server calls the mingetty program by looking at /etc/inittab. You will see a block like below:

# Run gettys in standard runlevels
1:2345:respawn:/sbin/mingetty tty1
2:2345:respawn:/sbin/mingetty tty2
3:2345:respawn:/sbin/mingetty tty3
…

There are many things we can do on daily basis which can make our lives better and make future better for our kids and ourselves. Most of these things are overlooked or not stressed enough. Lets start with cheap way to save some money and make world a better place.

Replace all the bulbs [...]