Pointers re bash status script

Question

To try and come to grips with bash scripting, I have been working on a basic status script for my laptop. What I have at the moment has all the functionality that I need and, more importantly, it works.
However, as it runs in a loop and as you never know what you don't know, I would really appreciate any comments about the approach I have used.
Please don't rewrite the script, just point out things I might want to look at to make it more efficient and/or more elegant/correct. Apart from Procyon's line, most of it is stuff I have cobbled together. The $BAT stuff seems particularly kludgy...
Brutal criticism is welcome, as long as it is constructive
# edit - so much for extensive testing. Moved the $CHG line into the loop where it could actually update
#!/bin/bash
# Status script for wmfs
RED="\\#BF4D80\\"
YEL="\\#C4A1E6\\"
BLU="\\#477AB3\\"
GRN="\\#53A6A6\\"
CYN="\\#6096BF\\"
MAG="\\#7E62B3\\"
GRY="\\#666666\\"
WHT="\\#C0C0C0\\"
while true;
do
# Collect system information
CHG=`acpi -V | awk '{ gsub(/,/, "");} NR==1 {print $4}'`
BAT=`acpi -V | if grep -q "on-line"; then echo $BLU"AC"; else echo $RED$CHG; fi`
MEM=`free -m | awk '/Mem/ {print $3}'`
# CPU line courtesy Procyon: https://bbs.archlinux.org/viewtopic.php?pid=661592
CPU=`eval $(awk '/^cpu /{print "previdle=" $5 "; prevtotal=" $2+$3+$4+$5 }' /proc/stat); sleep 0.4;
eval $(awk '/^cpu /{print "idle=" $5 "; total=" $2+$3+$4+$5 }' /proc/stat);
intervaltotal=$((total-${prevtotal:-0}));
echo "$((100*( (intervaltotal) - ($idle-${previdle:-0}) ) / (intervaltotal) ))"`
HD=`df -h | awk '/^ |sd/ {if (NF==5) print $4; else if (NF==6) print $5}'`
PCM=`exec "/home/jason/Scripts/pacman-up.pl"`
INT=`host google.com>/dev/null; if [ $? -eq 0 ]; then echo $GRN"ON"; else echo $RED"NO"; fi`
DATE=`date "+%I:%M"`
# Pipe to status bar
wmfs -s 0 "$GRY[BAT $BAT$GRY] [CPU $YEL$CPU%$GRY MEM $CYN$MEM$GRY] [HDD $MAG$HD$GRY] [PAC $BLU$PCM$GRY] [NET $INT$GRY] • $WHT$DATE"
sleep 5
done
Last edited by jasonwryan (2010-12-28 06:52:25)

Answer 1

Thanks rockin turtle. I tried your suggestion, but couldn't get it to play nicely with the rest of the
script. So I am using Procyon's. I'm not sure what is wrong with eval, but I will live with it for the time being.
I have made quite a few changes based on everyone's input. Thank you all.
The finished product? At least for now:
#!/bin/bash
# Status script for wmfs
RED="\\#BF4D80\\"
YEL="\\#C4A1E6\\"
BLU="\\#477AB3\\"
GRN="\\#53A6A6\\"
CYN="\\#6096BF\\"
MAG="\\#7E62B3\\"
GRY="\\#666666\\"
WHT="\\#C0C0C0\\"
# Collect system information
CHG=$(acpi -V | awk '{ gsub(/,/, "");} NR==1 {print $4}')
BAT=$(grep -q "on-line" <(acpi -V) && echo $BLU"AC" || echo $RED$CHG)
MEM=$(awk '/Mem/ {print $3}' <(free -m))
# CPU line courtesy Procyon: https://bbs.archlinux.org/viewtopic.php?pid=661592
CPU=$(eval $(awk '/^cpu /{print "previdle=" $5 "; prevtotal=" $2+$3+$4+$5 }' /proc/stat); sleep 0.4;
eval $(awk '/^cpu /{print "idle=" $5 "; total=" $2+$3+$4+$5 }' /proc/stat);
intervaltotal=$((total-${prevtotal:-0}));
echo "$((100*( (intervaltotal) - ($idle-${previdle:-0}) ) / (intervaltotal) ))")
HD=$(awk '/^\/dev/{print $5}' <(df -P))
PCM=$("$HOME/Scripts/pacman-up.pl")
INT=$(host google.com>/dev/null && echo $GRN"ON" || echo $RED"NO")
DTE=$(date "+%I:%M")
# Pipe to status bar
wmfs -s "$GRY[BAT $BAT$GRY] [CPU $YEL$CPU%$GRY MEM $CYN$MEM$GRY] [HDD $MAG$HD$GRY] [PAC $BLU$PCM$GRY] [NET $INT$GRY] • $WHT$DTE"