Bash script error [: !=: unary operator expected

Question

In my script I am trying to error check if the first and only argument is equal to -v but it is an optional argument. I use an if statement but I keep getting the unary oper

Answer 1

Quotes!

if [ "$1" != -v ]; then

Otherwise, when $1 is completely empty, your test becomes:

[ != -v ]

instead of

[ "" != -v ]

...and != is not a unary operator (that is, one capable of taking only a single argument).