If you’re like most ssh users when your connection breaks it’s bad news for you. Not only do you have to reconnect but your session gets destroyed and you have to make all the moves to restore the previous state. This doesn’t have to be that way. I’d like to say some words about two tools that solve these problems in the most elegant way possible.

tmux

tmux is a terminal multiplexer: it enables a number of terminals to be created, accessed, and controlled from a single screen. tmux may be detached from a screen and continue running in the background, then later reattached.

In the world of tmux there are windows and panes within windows. You can think of tmux windows as workspaces on the desktop that are aligned in a horizontal manner. It’s like having a number of virtual monitors next to each other each running different shell sessions. You can move across these windows as desired. With the use of panes you can split individual windows horizontally and/or vertically as desired, each pane housing a different session. This is pretty useful for tailing various log files in different panes and monitoring them at once.

You simply have to run the tmux command to create a new tmux session. Once a session exists upon reconnecting over ssh you have to invoke tmux attach to reconnect to your already existing session.

If you’re like me you may want to use tmux by default upon ssh’ing to servers. To make this happen you have to include export LC_TMUX_SESSION_NAME=yourusername into your ~/.bashrc and wrap scp on the client side and invoke tmux automatically on the server side. On a related note you can also take a look at my tmux.conf which I believe defines more intuitive shortcuts than the default configuration.

There are a number of alternatives to tmux that I’d like to list starting with the most powerful towards the least powerful. GNU Screen is yet another terminal multiplexer but its feature set, usability and configurability is rather limited compared to tmux. dtach is like a minimalistic tmux featuring one pane inside one window and it only provides a minimal set of options. Finally, with the use of the nohup command you can make your (typically long-running) script immune to hangups and hence it can survive ssh disconnects.

mosh

Remote terminal application that allows roaming, supports intermittent connectivity, and provides intelligent local echo and line editing of user keystrokes.

mosh is the other piece of the puzzle leading to the remote shell nirvana. After apt-getting mosh on the client and mosh-server on the server instead of invoking ssh yourserver.com invoke mosh yourserver.com. From this point on you don’t have to worry about reconnecting to ssh or having to wait for the server to echo back your characters anymore.

Ever felt that you have too many cables in your home and don’t know which one leads where?  Welcome to my world!  Here’s my recipe to how to make the situation easier.

It all starts with a sticky tape.

Now comes the pen.

Let’s cut the tape with scissors.

At this point you should remove the protective foil from the back of the tape to expose the glue and shape a loop.

As a final move, pull the cable through the loop and push the tape against the cable to make it stick.

When doing all the above properly, you’ll get a of sight that makes the pants of any nerd wet.

Here’s the situation: I have a Mini-ITX home server in my LAN that sometimes gets disabled when the power goes down. I could setup its BIOS to get automatically enabled when it gets power but considering the nature of power outages it may happen that the power goes out and on in rapid succession over a short amount of time which isn’t really good for the hardware.

I’d rather choose my server to be checked on a 5 minute basis and have it automatically woken up and I also wanna be notified by email on such an occasion so that I can SSH into it and uncrypt the crypto partition.

I’m about to carry out this task using my OpenWrt driven router. Everything is pretty straightforward, except that I can’t send emails through GMail SMTP using Openwrt because mini_sendmail lacks SASL support so I’ll just fetch a PHP script that’ll actually send the mail.

openwrt:/usr/bin/supervise-host

Be aware that the above wol utility is a home-cooked one.

openwrt:/etc/crontab/root

# m h  dom mon dow   command
0,5,10,15,20,25,30,35,40,45,50,55 * * * * supervise-host mybox http://mydomain.com/notifyme.php

At this ponit restart cron on OpenWrt.

mydomain.com:/var/www/notifyme.php

< ?php
mail('admin@mydomain.com', $_GET['host'] . ' has been rebooted', 'uncrypt me!');
?>

Enjoy!