Sorry just checked, if you're planning on simple cut/paste of your post into script. There are two double-quotes at the end of first echo and the echos don't read well in 80 character wide terminal. Something like this please if you don't mind, thanks.
if [ -n "$2" ]; then
echo "Warning: only one SCE per sce-update session can be entered in command line."
echo "Run 'sce-update' to check more than one SCE per session."
exit 1
fi