error handling with SFTP

I'm struggling with error handling with SFTP and QP2SHELL.

I created a generic shell script file that accepts parms:

#!/bin/sh
fromfile=$1
tofile=$2
user=$3
tgtsys=$4
totmpfile=$5
errlvl=$6
sftp $errlvl $user@$tgtsys << EOT
put $fromfile $totmpfile
rename $totmpfile $tofile
quit
EOT

If the put fails, it will still do the rename. And retrieving the
result out using the QUSRJOBI api always returns success.

So I am thinking that it will not work unless I execute sftp instead
of sh. I want to try that, but am wondering if I can pass parms to an
sftp file:

put $fromfile $totmpfile
rename $totmpfile $tofile

Or do I need to either have a script file for each sftp that I will
do, or create the file dynamically each time?

Just trying to understand the rules!
Thanks,

Phil