More syntax errors

A fundamental problem with shell scripts is syntax errors don't usually show up until the line with the problem is parsed by the interpreter. Here's a common error that I still find myself doing more than I should. See if you can locate the problem by just reading the script:

Chapter 9 - Script 3

#!/bin/sh
#
# 6/7/2017
#
echo "Chapter 9 - Script 3"

if [ $# -ne 1 ] ; then
 echo "Usage: script3 parameter"
 exit 255
fi

parm=$1
echo "parm: $parm"

if [ "$parm" = "home" ] ; then
 echo "parm is home."
elif if [ "$parm" = "cls" ] ; then
 echo "parm is cls."
elif [ "$parm" = "end" ] ; then
 echo "parm is end."
else
 echo "Unknown parameter: $parm"
fi

echo "End of script3"
exit 0

Here's the output:

Did you find my mistake? When I code an if...elif...else statement, I tend to copy and paste the first if statement. I then prepend elif to the next statement but forget to remove the if. This gets me almost every time.

Look at how I ran this script. I started first with just the name...