seeking help with shell script

I am trying to update a script which I had created to monitor tablespace usage.
Originally the sql spooled out to a text file anything with more than 75% used.
I have been asked to change this.
Now the sql must spool out all tablespaces.
The script I have to write should scan the file for values over 75% and if it encounters any it sends a high importance/priority email to the DBAs.
If no values above 75 are enountered it just sends out an informational email.
The bit I am having trouble with is the files scan for values 75 and over.
Any ideas from anyone?

Would be of assistance to yourself to provide some insight as to type of shell you are using, platform and what you have so far in the way of your script.

Cheers,
Cameron

The script I have is as follows from AIX 5L.
The bit i was trying to figure out is in bold. Took a bit of experimentation to get it right.

#!/usr/bin/sh
PATH=/usr/bin:/etc:/usr/sbin:/usr/ucb:$HOME/bin:/usr/bin/X11:/sbin:/usr/local/bi
n:/oracle/app/oracle/product/9.2.0/bin:.
export PATH

export DISTRIBUTION='****@*******.co.uk'

export TODAY=`date +'%d/%B/%Y'`
TNS_NAME=$1
export TNS_NAME
export ORACLE_HOME=/oracle/app/oracle/product/9.2.0
export ORAENV_ASK=NO
export warning_limit=75

PASSWORD=`grep $TNS_NAME ~oracle/dba_scripts/PASSWORDS/secure |cut -f2`
export PASSWORD

cd /oracle/dba_scripts

sqlplus /nolog <<EOF

connect system/$PASSWORD@$TNS_NAME
@/oracle/dba_scripts/percent_used1.sql
exit
EOF

export TBS_WARNINGS=`cat percent_used1.txt | awk '{print $2}'|sort -u -n -r|head -n1`
if [ $TBS_WARNINGS -ge $warning_limit ]
then
mailx -s"***CRITICAL*** Space report for "$TNS_NAME" on "$TODAY DISTRIBUTION < percent_used1.txt
else
mailx -s"Space report for "$TNS_NAME" on "$TODAY $DISTRIBUTION < percent_used1.txt

sleep 120
rm /oracle/dba_scripts/percent_used1.txt
exit 1
fi

Can you please provide the existing sql which use to spool only 75% used space, so that we can look insight what type of files it generating.....and then we could trace out....how to write the script

I got the Unix script sorted.
See my second post.

The script above produces the email as I needed.