Introduction
While developing, playing or working on Linux systems, a dynamic MotD generator script can quickly give you an overview of all used components of your Linux systems. FireMotD can show you this information in a sanitized and colorful way when you are logging in with SSH or console.
Over the past years I’ve been working on the ultimate MotD generator which can be tuned with themes and easily extended. Not having to manually check for available updates, check the server load or how many users are logged on can really save yourself some valuable time. Depending of the chosen theme FireMotD will output all information defined in the theme on your server.
You can find the latest release on GitHub.
Themes
At this moment there are 5 themes you can choose.
– Three 256 color themes: ‘Gray’, ‘Invader’, ‘Modern’, ‘Original’
– Three 16 color themes: ‘Clean’, ‘Blue’, ‘Red’
– One Html theme ‘Html’
256 Colors
Modern
Original
Orange
16 Colors
Blue
Red
Gray
Html
Bash Colors
Most terminals are not just able to display black and white, they can also display colors thanks to escape sequences which are composed of an escape character (in Bash backslash \ ) followed by some other characters. For using one of the 256 colors on the foreground or text color, the control sequence is: \e[0;<colornumber>m
If you want to edit one of the 256 colors on the background, the control sequence is: \e]48;5<colornumber>m
FireMotD contains a nice and useful colortest:
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FireMotD -C |
And a colormap with the numbers for the control sequences:
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FireMotD -M |
You can find more information about terminals and colors here.
Terminal Emulators
It took me some time to figure out the best console emulator which supports 256 colors. With the help of some Cmder power users in this GitHub issue, I was pointed out that the development version of Cmder has an integrated mintty thanks to Babun. At the moment I’m still using this task, which launches a tab in Conemu or Cmder with a 256 color SSH session.
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"%userprofile%\.babun\cygwin\bin\mintty.exe" /usr/bin/ssh root@server -new_console:t:server-root |
An alternative to using mintty, would be to use the msys connector, created by Maximus. As Maximums points out
Running bash from mintty in ConEmu looks like running bash inside Ubuntu inside VirtualBox in Windows. Check cygwin/msys connector developed specially for ConEmu.
So I gave his msys connector a try and after some small issues and some help of Maximum, I got it working. It works fine, but still has some minor flaws imho:
- No right-click paste
- Weird output with some commands such as top
- When the console windows is resized, colors get scrambled.
You need to copy the executable of the Connector into the bin folder of your cygwin installation and create a task which executes the correct Connector. Please read through this ConEmu documentation. The task I’m using with the Connector looks like this:
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conemu-cyg-64.exe -cur_console:h0 /usr/bin/ssh user@server |
How to use MotD generator?
System Install
You need to have make installed on the system, if you want to use the Makefile.
To install to /usr/local/bin/FireMotD
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sudo make install |
With this you can probably run FireMotD from anywhere in your system. If not, you need to add /usr/local/bin to your$PATH variable. To adjust the installation path, change the var IDIR=/usr/local/bin in the Makefile to the path you want.
To install bash autocompletion support
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sudo make bash_completion |
With this you can use TAB to autocomplete parameters and options with FireMotD. Does not require the sudo make install above (system install), but requires the bash-completion package to be installed and working. Then you should logout-login or source the bash completion file, eg. $ . /etc/bash_completion.d/FireMotD
If you don’t have root access, just install everything on your user’s folder and source the file from your user’s .profile file
Crontab to get system updates count
This is an example on how to record the system update package count daily.
This will update the file /var/tmp/updatecount.txt for later access.
Root privilege is required for this operation.
To edit root’s crontab
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sudo crontab -e |
Then add this line (updates everyday at 3:03am)
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3 3 * * * /usr/local/bin/FireMotD -S > /dev/null |
Or using the old way
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3 3 * * * /usr/local/bin/FireMotD -U > /var/tmp/updatecount.txt |
Adding FireMotD to run on login
Choosing where to run your script is kind of situational. Some files will only run on remote logins, other local logins, or even both. You should find out what suits best your needs on each case.
To add FireMotD to a single user
Edit the user’s ~/.profile file, ~/.bash_profile file, or the ~/.bashrc file
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nano ~/.profile |
Add the FireMotD call at the end of the file (choose your theme)
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/usr/local/bin/FireMotD -t red |
To add FireMotD to all users
You may call FireMotD from a few different locations for running globally.
Eg /
etc/bash.bashrc and
/etc/profile .
You may also create a initialization script, for example
init.sh which will call the FireMotD script in
/etc/profile.d when logging in. You can put whatever you like in this init.sh script. Everything in it will be executed at the moment someone logs in your system. Example:
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#!/bin/bash /usr/local/bin/FireMotD --Theme Red |
MotD Generator Components
Script Version
To make it easy to see what version of generate_motd.sh you are using, I integrated the version in the frame of the MotD.
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ScriptName="`readlink -e $0`" ScriptVersion=" `cat $ScriptName | grep "# Version:" | awk {'print $3'} | tr -cd '[[:digit:].-]' | sed 's/.\{2\}$//'` " |
Ip
I changed the method of retrieving the ip address. As CentOS 7 has different naming conventions, it seem a more solid method to use ip route.
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ip route get 8.8.8.8 | head -1 | cut -d' ' -f8 |
Release
It’s always useful to know what Linux release your are working on.
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cat /etc/*release | head -n 1 |
Kernel
Knowing the exact kernel version can also contribute to learning to know your servers
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uname -rs |
Uptime
I found this command to be working best on most systems. It is also capable of showing the number of days, hours, minutes and seconds. I also found it more useful then just using ‘uptime‘.
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awk '{print int($1/86400)" day(s) "int($1%86400/3600)":"int(($1%3600)/60)":"int($1%60)}' /proc/uptime |
Average CPU Utilization
CPU utilization is a little harder as you prefer to get the average CPU utilization. To achieve this I’m using mpstat.
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CpuUtil=`LANG=en_GB.UTF-8 mpstat 1 1 | awk '$2 ~ /CPU/ { for(i=1;i<=NF;i++) { if ($i ~ /%idle/) field=i } } $2 ~ /all/ { print 100 - $field}' | tail -1` |
I also prefer to see the number of cores in the output:
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CpuProc="`cat /proc/cpuinfo | grep processor | wc -l` core(s)." |
Detect virtualization technique or hardware platform
‘dmesg’ is a command on most Unix-like operating systems that prints the message buffer of the kernel. It’s a useful command for the MotD generator as it doesn’t require any special permissions.
- Qemu with KVM
12Platform=`dmesg | grep "DMI:" | sed 's/^.*QEMU/QEMU/' | sed 's/, B.*//'`
- VMware
1Platform=`dmesg | grep "DMI:" | sed 's/^.*VMware/VMware/' | sed 's/, B.*//'`
- Fujitsu Primergy
1Platform=`dmesg | grep "DMI:" | sed 's/^.*FUJITSU PRIMERGY/Fujitsu Primergy/' | sed 's/, B.*//'`
On some systems, you could get an ‘Unknown’ result. Please let me know on GitHub by making an issue. You should be able to find the correct platform with dmesg, cut and sed.
Cowsay and other ASCII generators
Something old school that exists for a really long time is Cowsay, which is a configurable speaking ASCII cow. I’ve seen several people integrate it in their MotD, but personally I think it does not fit into an enterprise. Something to play with at home though. You can even make it say a random expression every time you log in. Here you can find an implementation of Cowsay where you can output to html, text or even Json. And here you can find a Python implmentation of Cowsay. I also stumbled on Christopher Johnson’s ASCII Art Collection , an ascii archive containing a massive amount of ASCII art examples. The website is kind of outdated, but check it out if you like ascii art or if you are looking for something to integrate into your MotD. If you want convert some text to ASCII, check out this website or this one where you can enter some text, choose a font, character width and height and see the result immediately. If you want to convert an image to ASCII, check out this website.
(Almost) Final words
It might seem like a small tool, but my MotD generator can really help you get a quick overview of your Linux server state. I’ll try to extend the tool when I find the time, as I still have some ideas left which can improve it. Let me know on the Nagios Exchange what you think of my plugin by rating it or submitting a review. Please also consider starring the project on GitHub.