[Solved] Auto update of variables

Question

I am modifying another's script by having it call on two variables. The variables need to be able to update automatically after they have been initialized. I sense the solution easy but all my search querys have not yielded any answers. The variables in question are $MONTH and $YEAR. Thank you.
#!/bin/bash
MONTH=$(date --date=now +%m)
YEAR=$(date --date=now +%g)
aurum ()
if [ "$MONTH" == "01" ]; then
printf "F$YEAR"
elif [ "$MONTH" == "02" ]; then
printf "G$YEAR"
elif [ "$MONTH" == "03" ]; then
printf "H$YEAR"
elif [ "$MONTH" == "04" ]; then
printf "J$YEAR"
elif [ "$MONTH" == "05" ]; then
printf "K$YEAR"
elif [ "$MONTH" == "06" ]; then
printf "M$YEAR"
elif [ "$MONTH" == "07" ]; then
printf "N$YEAR"
elif [ "$MONTH" == "08" ]; then
printf "Q$YEAR"
elif [ "$MONTH" == "09" ]; then
printf "U$YEAR"
elif [ "$MONTH" == "10" ]; then
printf "V$YEAR"
elif [ "$MONTH" == "11" ]; then
printf "X$YEAR"
elif [ "$MONTH" == "12" ]; then
printf "Z$YEAR"
fi
C_YAHOO_FINANCE_URL="http://download.finance.yahoo.com/d/quotes.csv?f=sl1k2&s=SI$(aurum).CMX+GC$(aurum).CMX+CL$(aurum).NYM+^TNX+^VIX+^GSPC+^IXIC+^FTSE+^GDAXI+^N225+^HSI"
while true
do
TICKER=$(curl -s "$C_YAHOO_FINANCE_URL")
clear
echo "$TICKER" | while read line;
do
if [[ $line == *+* ]]
then
echo -e "\e[00;32m$line" | tr -s ',^"' ' '
else
echo -e "\e[00;31m$line" | tr -s ',^"' ' '
fi
done
sleep 20s
done
Last edited by Divinorum (2013-06-18 23:57:07)

Answer 1

Trilby wrote:
Really, case?  Array's are your friend:
month_name=(Zero F G H J K M N Q U V X Z)
aurum() {
echo ${month_name[$MONTH]}$YEAR
And this, of course, nullifies the need for a separate function to do this - just use ${month_name[...]} wherever you need it.
Many thanks this was a great fix. Nice and clean.
Trilby wrote:
As for the original problem, why not just restart the script once a mont??
If you really want it automated, make a cron job that kills the script and restarts it on the first second of the first day of every month.
That was my first solution but my friend challanged me to consolidate all the work in this one script. Also, if there's a fix for self-updating variables in a script doesn't that increase its portability? I know many people who would be interested in having a command line market ticker but having to add crons for gold, silver, oil and other commodities diminishes the appeal. Mostly I am interested in the challange of editing the script to have self-updating variables. I don't know if this is possible but I am pursuing it.
Trilby wrote:
And the curl to variable then echo variable to pipe is odd.  Just "curl url... | while read line".  I see the 'clear', which makes me think you don't want to see the curl progress.  But if that is the reason, it still would flash on the screen every 20 seconds.  Instead, just redirect curl's stderr to /dev/null.  EDIT: curl does have such a flag:
curl -s <someurlbits>${month_name[$MONTH]}$YEAR<otherurlbits> | while read line
This single line will cut 30 some lines from your original.
The flash was a seamless blink on each update that rarely caught my eye. Your solution does remove that but now the shell is not cleared on each update and thus the old quotes stay on top of the new. Perhaps I am missing something basic.