12.9. The Elegant Useless Clock Prompt

This is one of the more attractive (and useless) prompts I've made. Because many X terminal emulators don't implement cursor position save and restore, the alternative when putting a clock in the upper right corner is to anchor the cursor at the bottom of the terminal. This builds on the idea of the "termwide" prompt above, drawing a line up the right side of the screen from the prompt to the clock. A VGA font is required.

Note: There is an odd substitution in here, that may not print properly being translated from SGML to other formats: I had to substitute the screen character for \304 - I would normally have just included the sequence "\304", but it was necessary to make this substitution in this case.


#   This prompt requires a VGA font.  The prompt is anchored at the bottom
#   of the terminal, fills the width of the terminal, and draws a line up
#   the right side of the terminal to attach itself to a clock in the upper
#   right corner of the terminal.

function prompt_command {
#   Calculate the width of the prompt:
hostnam=$(echo -n $HOSTNAME | sed -e "s/[\.].*//")
#   "whoami" and "pwd" include a trailing newline
#   Add all the accessories below ...
let promptsize=$(echo -n "--(${usernam}@${hostnam})---(${PWD})-----" \
                 | wc -c | tr -d " ")
#   Figure out how much to add between user@host and PWD (or how much to
#   remove from PWD)
let fillsize=${COLUMNS}-${promptsize}
#   Make the filler if prompt isn't as wide as the terminal:
while [ "$fillsize" -gt "0" ] 
   # The A with the umlaut over it (it will appear as a long dash if
   # you're using a VGA font) is \304, but I cut and pasted it in
   # because Bash will only do one substitution - which in this case is
   # putting $fill in the prompt.
   let fillsize=${fillsize}-1
#   Right-truncate PWD if the prompt is going to be wider than the terminal:
if [ "$fillsize" -lt "0" ]
   let cutt=3-${fillsize}
   newPWD="...$(echo -n $PWD | sed -e "s/\(^.\{$cutt\}\)\(.*\)/\2/")"
#   Create the clock and the bar that runs up the right side of the term
local LIGHT_BLUE="\033[1;34m"
local     YELLOW="\033[1;33m"
#   Position the cursor to print the clock:
echo -en "\033[2;$((${COLUMNS}-9))H"
echo -en "$LIGHT_BLUE($YELLOW$(date +%H%M)$LIGHT_BLUE)\304$YELLOW\304\304\277"
local i=${LINES}
echo -en "\033[2;${COLUMNS}H"
#   Print vertical dashes down the side of the terminal:
while [ $i -ge 4 ]
   echo -en "\033[$(($i-1));${COLUMNS}H\263"
   let i=$i-1

let prompt_line=${LINES}-1
#   This is needed because doing \${LINES} inside a Bash mathematical
#   expression (ie. $(())) doesn't seem to work.


function clock3 {
local LIGHT_BLUE="\[\033[1;34m\]"
local     YELLOW="\[\033[1;33m\]"
local      WHITE="\[\033[1;37m\]"
local LIGHT_GRAY="\[\033[0;37m\]"
local  NO_COLOUR="\[\033[0m\]"

case $TERM in

$YELLOW\$(date \"+%a,%d %b %y\")\