nescafe

Incorrect. Word splitting does not happen in [[ ]] tests. The only reason I had the [[ -f $file ]] || continue is to handle the case where there are no .java files, which will cause the for loop to iterate once with file set to '*.java'. i could have also used nullglob,but chose not to.

Linked article is actually a really horrible intro to bash -- at best, it is an OK intro to pre-POSIX bourne shell scripting.

Specifically:

* test and [ ] are fraught with parameter expansion peril. Use [[ ]] instead.

* The author uses single quotes around strings that are demonstrating parameter expansion. Single quotes inhibit parameter expansion, so every one of those examples is wrong.

* select is a better tool than read; case for most of his case-relasted demos.

* Backticks ( ` ` ) are the devil.

At least he points people greg's wiki at the end.

Find is overkill for this.

  for file in *.java; do
     [[ -f $file ]] || continue
     javac "$file"
  done

No, that is just wrong. In double-brackets, bash will handle expansion and testing of unset variables and variables with spaces just fine, because word splitting and pathname expansion are not performed in double braces -- they are shell syntax, as opposed to single brackets, which are commands. Your syntax error happened because you don't have a fi matching that if.

As a counterexample:

  (echo $BASH_VERSION; 
  foo=foo; [[ $foo = foo ]] && echo $foo; 
  foo="1 2 3"; [[ $foo = "1 2 3" ]] && echo $foo; 
  foo=''; echo ${foo?"No foo for you"}; 
  unset foo; echo ${foo?"No foo for you"})
  4.2.10(1)-release
  foo
  1 2 3
  
  bash: foo: No foo for you

That last one is one of the few ways you can tell whether a variable is unset or merely set to an empty string.

lrn2bash.