What does "unary operator expected" mean
The bash message
unary operator expected
means that you do a comparison where one site is empty for example
if [ $name = "foo" ]
and $name is empty. Then the bash shell internally replaces $name by an empty string and it will be interpreted as
if [ = "foo" ]
and this is not a valid expression.
The solution is to quote variable names like this:
if [ "$name" = "foo" ]
Then it will work.
Shell scripting tutorial
Try the tutorial BaBE - Bash By Examples to avoid this and similar mistakes in the future.
Debugging bash scripts
tweedleburg:~ # bash -x test.sh + echo 'how is your name? ' how is your name? + read name + '[' = foo ']' test.sh: line 3: [: =: unary operator expected