Now do [ ... ] and [[ ... ]]

I'm still not sure when to use one or the other. I use double brackets by default until something doesn't work.

The ultimately sad part was the professor in a Sun OS machine.

In a corner with no where to go, giving demerits because his bash was older than he realized.

Reminds me of my college professor that claimed you don’t have to close HTML tags (some you absolutely do) and I proved that you do. Not all of them, but most of them. (Netscape Navigator Days)

> When I was a young, green, university student, I was forced to use test(1) as the only true way to do testing in shell scripting. […] Yeah, I was also forced to not use semicolons as they were evil (according to my professor, any comment unneeded!).

The author’s professor clearly went gone overboard, but doesn’t this entire anecdote demonstrate the value of teaching it this way? Having green students call the `test` binary provides more insight into how UNIX operates, and gets them into that mindset.

Nowadays [ is a builtin. The subprocess for a simple branch would be excessive overhead.

   $ which [
   /bin/[
   $ type [
   [ is a shell builtin

   $ which test
   /bin/test
   $ type test
   test is a shell builtin

So if you really want to troll someone, you can put them in quotes.

  if "[" "$foo" "==" "bar" "]"; then ...

Here's Greg's Wiki about the difference between [, [[ and test

https://mywiki.wooledge.org/BashFAQ/031