How do I store an argument as a string in the script?

Arguments are avaialble in a script as $1, $2, etc. You can just assign them to another variable if you wish to store them with a more meaningful name, e.g. OUTPUTFILE=$1. Is that what you mean?

Yes, I tried that.
I'm writing a script to count the total number of occurrences in files entered as arguments with $1 as the pattern.
Here's what I have:

#!/bin/bash

n="$1"
total=0
while [$# -ge 2]; do
sed "s/$n/$n\n/g" $2
total=$[total+(grep -c $n $2)]
shift
done
echo $total


and it's not working.
Thanks

Try changing this line:

Also you need a space between [ and $#, and 2 and ] in the while statement.

I tried those and the terminal says:
n="pattern: command not found
total=0: command not found
while: expression syntax

Are you sure it's running in bash? How are you executing it exactly? And what OS are you running under?