Bash: [: =: unary operator expected

[: =: unary operator expected

Use:

if [ "$aug1" = "and" ];

because otherwise, if $aug1 is undefined or empty, it vanishes from the scene of the crime, leaving only

if [ = "and" ];

which is not valid.

With the modern [[, you don’t need to worry about that. It has lots of other nice features, too.