I need a unix script that will check the size of multiple files in the same directory or from a text file.

that will check the size of multiple files

What do you mean by check ?

Here is a script that will tell you the file size in bytes.

#! /bin/sh

ls > listing.txt

while read file
do
echo "Size of $file`stat -c=%s $file`"
done < listing.txt

I tried manipulating the code and got an error that -c was not a valid option. When I tried the valid options, I got a rather complete list of stats, not just a numeric value for file size

How about

stat --format=%s $file

stat -c=%s $file

-c

--format

try ...

ls -l *

while read afile
do
    ls -l $afile
done < listfile

ls -l | awk -F" " '{ print $5,$9 }'

Here is a script I have done to compile everyday statistics about files on the system. Let's say here, all files bigger than 500Mg.

REP=/home/user
LOG=filecheck.log
DATE=`date`

date >> $REP/$LOG

find . -size +1000000 -exec ls -l {} \; >>$REP/$LOG