Message of the day: Banner-Message¶

Preliminary note motd¶

You may find additional useful information at

• http://wiki.centos.org/TipsAndTricks/BannerFiles

Setup motd¶

The /etc/motd is a file on Unix-like systems that contains a "message of the day".
This file is just static text, therefore we recreate this file every 10 mins with updated information.

I want to say first that this is not the only way of setting up such a system. There are many ways of achieving this goal but this is the way I take.

add script¶

vim /usr/local/bin/gen_motd.sh

basic example:

#!/bin/bash
# JKE 2011-05-14
# create /etc/motd
# to be called by /etc/cron.d/gen_motd
#
echo -e " 
*******************************************************************
* xxyyy Janus Server                                            *
*
======h1.                                            *
*                                                               *
* This system is for the use of authorized users only. Usage of *
* this system will be monitored and recorded by system personnel. *
*                                                               *
* Anyone using this system expressly consents to such monitoring*
* and is advised that if such monitoring reveals possible       *
* evidence of criminal activity, system personel may provide the*
* evidence from such monitoring to law enforcement officials.   *
*                                                               *
*******************************************************************
* Version   = `cat /etc/centos-release`
* Kernel    = `uname -r`
* Uptime    = `uptime | sed 's/.*up \([^,]*\), .*/\1/'`
* Mem /free = `cat /proc/meminfo | grep MemTotal | awk {'print $2'}` kB / `cat /proc/meminfo | grep MemFree | awk {'print $2'}` kB 
* Swap/free = `cat /proc/meminfo | grep SwapTotal | awk {'print $2'}` kB / `cat /proc/meminfo | grep SwapFree | awk {'print $2'}` kB
* last updt = `date`
*******************************************************************
" > /etc/motd

set shell-script being executeable

chmod +x /usr/local/bin/gen_motd.sh

add script to cron¶

vim /etc/cron.d/gen_motd

basic example:

# JKE 2011-05-14
#
#    min            hr    dom    month    dow    user    command
#    -            -    -    -    -
#    |            |    |    |    |
#    |            |    |    |    +-day of week (0-7) sunday=0 or 7
#    |            |    |    +---------month (1-12)
#    |            |    +-----------------day of month (1-31)
#    |            +-------------------------hour (0-23)
#    +-------------------------------------------------min (0-59)
# 
    5,15,25,35,45,55    *    *    *    *    root    /usr/local/bin/gen_motd.sh

Test¶

• recreate motd manually
• login and check the output (you should see the motd)
  

  /usr/local/bin/gen_motd.sh
  ssh root@localhost
  exit
  

• wait minimum 10 mins
• login once more, you should have an updated output