i have the following function that should figure out a percentage (you call the function with 5 parameters obviously):

function countresponses()
{
totalresponses=`expr $1 + $2 + $3 + $4 + $5`
badresponses=`expr $4 + $5`
percentbad=`expr $badresponses / $totalresponses * 100`
echo "Percent bad is: $percentbad"
}

but i keep getting an error:
expr: syntax error
Percent bad is:

ive tried a bunch of different ways to get a percentage, but i keep getting expr syntax errors of one type or another... i don't think this should be very hard, but its proving to be... any help would be appreciated

why not use bc?

you'll have to forgive my ignorance, but i'm not aware of the bc command... could you give an example please?

The syntax error is due to the multiplication symbol in expr: it should be \* not simply *, otherwise it is expanded by the shell as the wildcard character. Anyway, follow the suggestion of ghostdog74 and use bc instead. This will give you more accurate results, since in this way you can manage floating point values. You can also establish the number of decimal digits by setting the parameter scale. For example:

thank you for your help, it is now working good.... that bc command is a 1000 times better than expr!! much appreciated

Apart the examples me and ghostdog suggested, you will find plenty of tutorials about bc by googling around. You can find an explanation with some examples on the Advanced Bash Scripting Guide, here. Also you can look at
Another point, regarding the expr issue: in BASH you can use the ((...)) syntax, that is arithmetic expansion. It has a more intuitive syntax than expr (it permits the multiplication with * for example) and permits C style operations like increments +=. However, to manage floating point values you have to stick with bc or some other external commands that can manage them (awk, perl, python...).

ok, now that ive got the percentage as 15.00 (i used scale=2), im trying to do an if statement, but am getting an "expecting integer" error from the if statment... how can i change the bc result to an integer so i can use it in an if statement?

you can't really compare floating values in bash. show how you do your if statement, in fact show what you have.

here is my full function as of right now:

function countresponses()
{
totalresponses=`expr $1 + $2 + $3 + $4 + $5`
badresponses=`expr $4 + $5`
percentbad=$(echo "scale=2; $badresponses / $totalresponses * 100" | bc)

if [ $percentbad -gt 5 ];
then
echo "There is a problem with the modified filter, restoring old filter configuration."
# need to rebuild teh configuration here and test once more
# taillog
else
echo "The new configuration is working properly."
fi
}

and here is the error im getting:
./spamfilter: line 122: [: 15.00: integer expression expected
The new configuration is working properly.

it shouldnt get the to the else part, since 15 > 5 obviously

i found a way to convert the float to an int and now everything works properly... thanks for all the help

Please post your soln so we can all learn