Sophie

Sophie

distrib > Mandriva > 2010.1 > x86_64 > by-pkgid > 965e33040dd61030a94f0eb89877aee8 > files > 673

howto-html-en-20080722-2mdv2010.1.noarch.rpm

<HTML
><HEAD
><TITLE
>A "Proof of Concept" Example</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
REL="HOME"
TITLE="Bash Prompt HOWTO"
HREF="index.html"><LINK
REL="UP"
TITLE="Loading Prompt Colours Dynamically"
HREF="c670.html"><LINK
REL="PREVIOUS"
TITLE="Loading Prompt Colours Dynamically"
HREF="c670.html"><LINK
REL="NEXT"
TITLE="Prompt Code Snippets"
HREF="c679.html"></HEAD
><BODY
CLASS="SECT1"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>Bash Prompt HOWTO: </TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="c670.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 10. Loading Prompt Colours Dynamically</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="c679.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN672"
></A
>10.1. A "Proof of Concept" Example</H1
><P
>This is a "proof of concept" more than an attractive prompt: changing 
colours within the prompt dynamically.  In this example, the colour of the
host name changes depending on the load (as a warning).</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><FONT
COLOR="#000000"
><PRE
CLASS="PROGRAMLISTING"
>#!/bin/bash
#   "hostloadcolour" - 17 October 98, by Giles
#
#   The idea here is to change the colour of the host name in the prompt, 
#   depending on a threshold load value.

# THRESHOLD_LOAD is the value of the one minute load (multiplied
# by one hundred) at which you want
# the prompt to change from COLOUR_LOW to COLOUR_HIGH
THRESHOLD_LOAD=200
COLOUR_LOW='1;34'
          # light blue
COLOUR_HIGH='1;31'
           # light red

function prompt_command {
ONE=$(uptime | sed -e "s/.*load average: \(.*\...\), \(.*\...\), \(.*\...\)/\1/" -e "s/ //g")
#   Apparently, "scale" in bc doesn't apply to multiplication, but does
#   apply to division.
ONEHUNDRED=$(echo -e "scale=0 \n $ONE/0.01 \nquit \n" | bc)
if [ $ONEHUNDRED -gt $THRESHOLD_LOAD ] 
then 
    HOST_COLOUR=$COLOUR_HIGH
	# Light Red
else
    HOST_COLOUR=$COLOUR_LOW
	# Light Blue
fi
}

function hostloadcolour {

PROMPT_COMMAND=prompt_command
PS1="[$(date +%H%M)][\u@\[\033[\$(echo -n \$HOST_COLOUR)m\]\h\[\033[0m\]:\w]$ "
}</PRE
></FONT
></TD
></TR
></TABLE
><P
>Using your favorite editor, save this to a file named "hostloadcolour".  If
you have the Bashprompt package installed, this will work as a theme.  If you
don't, type <TT
CLASS="USERINPUT"
><B
>source hostloadcolour</B
></TT
> and then <TT
CLASS="USERINPUT"
><B
>hostloadcolour</B
></TT
>.
Either way, "prompt_command" becomes a function in your environment.
If you examine the code, you will notice that the colours ($COLOUR_HIGH and 
$COLOUR_LOW) are set using only a partial colour code, ie. "1;34" instead of
"\[\033[1;34m\]", which I would have preferred.  I have been unable to get
it to work with the complete code.  Please let me know if you manage this.</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="c670.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="index.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="c679.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Loading Prompt Colours Dynamically</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="c670.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Prompt Code Snippets</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>