Trying to retrieve first 5 characters from string in bash error?

Depending on your shell, you may be able to use the following syntax:

expr substr $string $position $length

So for your example:

TESTSTRINGONE="MOTEST"
echo `expr substr ${TESTSTRINGONE} 0 5`

Alternatively,

echo 'MOTEST' | cut -c1-5

or

echo 'MOTEST' | awk '{print substr($0,0,5)}'