Examining man test, I see that under synopsis for test are the possibilities test EXPRESSION and test. What does [ EXPRESSION ], [ ] and [OPTION mean below ?Why are the brackets empty and why does [OPTION miss a bracket ? Can someone interpret this for me ?NAME       test - check file types and compare valuesSYNOPSIS       test EXPRESSION       test       [ EXPRESSION ]       [ ]       [ OPTION
What does `[ EXPRESSION ], [ ] and [OPTION` mean in `man test`?
test