====Message of the Day for the Raspberry Pi====

Written in pure Bash. No need to install any package. Tested with the Arch Linux ARM and Raspbian distributions.

Download and save the motd.sh bash script in the Raspberry Pi. Remember to add execution permissions and change the owner:
   $ sudo chown root:root motd.sh
   $ sudo chmod +x motd.sh

The following steps may vary depending on the OS. Arch Linux ARM is assumed.

Autoexecute the script when the user logs in. There are multiple locations from where you can start the motd.sh script, for example using the /etc/profile. Save the motd.sh script in the directory /etc/profile.d and it will be executed after the login.
Remove the default MOTD. It is located in /etc/motd.
    $ sudo rm /etc/motd

Remove the "last login" information. Disable the PrintLastLog option from the sshd service. Edit the /etc/ssh/sshd_config file and uncomment the line #PrintLastLog yes:
    $ sudo nano /etc/ssh/sshd_config

Before:
    #PrintLastLog yes
After:
    PrintLastLog no

Note: If you don't see the degree Celsius character correctly (º) make sure you have enabled a UTF8 locale (Arch Linux locales).

Script:
   #!/bin/bash
   
   clear
   
   function color (){
     echo "\e[$1m$2\e[0m"
   }
   
   function extend (){
     local str="$1"
     let spaces=60-${#1}
     while [ $spaces -gt 0 ]; do
       str="$str "
       let spaces=spaces-1
     done
     echo "$str"
   }
   
   function center (){
     local str="$1"
     let spacesLeft=(78-${#1})/2
     let spacesRight=78-spacesLeft-${#1}
     while [ $spacesLeft -gt 0 ]; do
       str=" $str"
       let spacesLeft=spacesLeft-1
     done
     
     while [ $spacesRight -gt 0 ]; do
       str="$str "
       let spacesRight=spacesRight-1
     done
     
     echo "$str"
   }
   
   function sec2time (){
     local input=$1
     
     if [ $input -lt 60 ]; then
       echo "$input seconds"
     else
       ((days=input/86400))
       ((input=input%86400))
       ((hours=input/3600))
       ((input=input%3600))
       ((mins=input/60))
       
       local daysPlural="s"
       local hoursPlural="s"
       local minsPlural="s"
       
       if [ $days -eq 1 ]; then
         daysPlural=""
       fi
       
       if [ $hours -eq 1 ]; then
         hoursPlural=""
       fi
       
       if [ $mins -eq 1 ]; then
         minsPlural=""
       fi
       
       echo "$days day$daysPlural, $hours hour$hoursPlural, $mins minute$minsPlural"
     fi
   }
   
   borderColor=35
   headerLeafColor=32
   headerRaspberryColor=31
   greetingsColor=36
   statsLabelColor=33
   
   borderLine="━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━"
   borderTopLine=$(color $borderColor "┏$borderLine┓")
   borderBottomLine=$(color $borderColor "┗$borderLine┛")
   borderBar=$(color $borderColor "┃")
   borderEmptyLine="$borderBar                                                                              $borderBar"
   
   # Header
   header="$borderTopLine\n$borderEmptyLine\n"
   header="$header$borderBar$(color $headerLeafColor "          .~~.   .~~.                                                         ")$borderBar\n"
   header="$header$borderBar$(color $headerLeafColor "         '. \ ' ' / .'                                                        ")$borderBar\n"
   header="$header$borderBar$(color $headerRaspberryColor "          .~ .~~~..~.                      _                          _       ")$borderBar\n"
   header="$header$borderBar$(color $headerRaspberryColor "         : .~.'~'.~. :     ___ ___ ___ ___| |_ ___ ___ ___ _ _    ___|_|      ")$borderBar\n"
   header="$header$borderBar$(color $headerRaspberryColor "        ~ (   ) (   ) ~   |  _| .'|_ -| . | . | -_|  _|  _| | |  | . | |      ")$borderBar\n"
   header="$header$borderBar$(color $headerRaspberryColor "       ( : '~'.~.'~' : )  |_| |__,|___|  _|___|___|_| |_| |_  |  |  _|_|      ")$borderBar\n"
   header="$header$borderBar$(color $headerRaspberryColor "        ~ .~ (   ) ~. ~               |_|                 |___|  |_|          ")$borderBar\n"
   header="$header$borderBar$(color $headerRaspberryColor "         (  : '~' :  )                                                        ")$borderBar\n"
   header="$header$borderBar$(color $headerRaspberryColor "          '~ .~~~. ~'                                                         ")$borderBar\n"
   header="$header$borderBar$(color $headerRaspberryColor "              '~'                                                             ")$borderBar"
   
   me=$(whoami)
   
   # Greetings
   greetings="$borderBar$(color $greetingsColor "$(center "Welcome back, $me!")")$borderBar\n"
   greetings="$greetings$borderBar$(color $greetingsColor "$(center "$(date +"%A, %d %B %Y, %T")")")$borderBar"
   
   # System information
   read loginFrom loginIP loginDate <<< $(last $me --time-format iso -2 | awk 'NR==2 { print $2,$3,$4 }')
   
   # TTY login
   if [[ $loginDate == - ]]; then
     loginDate=$loginIP
     loginIP=$loginFrom
   fi
   
   if [[ $loginDate == *T* ]]; then
     login="$(date -d $loginDate +"%A, %d %B %Y, %T") ($loginIP)"
   else
     # Not enough logins
     login="None"
   fi
   
   label1="$(extend "$login")"
   label1="$borderBar  $(color $statsLabelColor "Last Login....:") $label1$borderBar"
   
   uptime="$(sec2time $(cut -d "." -f 1 /proc/uptime))"
   uptime="$uptime ($(date -d "@"$(grep btime /proc/stat | cut -d " " -f 2) +"%d-%m-%Y %H:%M:%S"))"
   
   label2="$(extend "$uptime")"
   label2="$borderBar  $(color $statsLabelColor "Uptime........:") $label2$borderBar"
   
   label3="$(extend "$(free -m | awk 'NR==2 { printf "Total: %sMB, Used: %sMB, Free: %sMB",$2,$3,$4; }')")"
   label3="$borderBar  $(color $statsLabelColor "Memory........:") $label3$borderBar"
   
   label4="$(extend "$(df -h ~ | awk 'NR==2 { printf "Total: %sB, Used: %sB, Free: %sB",$2,$3,$4; }')")"
   label4="$borderBar  $(color $statsLabelColor "Home space....:") $label4$borderBar"
   
   label5="$(extend "$(/opt/vc/bin/vcgencmd measure_temp | cut -c "6-9")ºC")"
   label5="$borderBar  $(color $statsLabelColor "Temperature...:") $label5$borderBar"
   
   stats="$label1\n$label2\n$label3\n$label4\n$label5"
   
   # Print motd
   echo -e "$header\n$borderEmptyLine\n$greetings\n$borderEmptyLine\n$stats\n$borderEmptyLine\n$borderBottomLine"