See below example:

$ ls -1p
$ find . -type f -name apple\*
$ find . -type f -name orange\*
$ find . -type f -name apple\* -o -name orange\*
$ find . -type f \( -name apple\* -o -name orange\* \)

I was surprised to discover I needed the parentheses for this to work as expected; apparently I haven't internalized the rule of precedence by which find evaluates its arguments.

How can I easily predict when I will and when I will not need to use parentheses to explicitly group find primaries?

Put another way, what are the rules by which I can imagine find inserting parentheses into the commands I give it, which will allow me to accurately predict how it will evaluate ungrouped expressions?


As per the documentation,

Please note that -a when specified implicitly (for example by two tests appearing without an explicit operator between them) or explicitly has higher precedence than -o. This means that find . -name afile -o -name bfile -print will never print afile.

So basically you can imagine find surrounding any two "anded" expressions with parentheses by default. Your

find . -type f -name apple\* -o -name orange\*

is interpreted as

find . \( -type f -name apple\* \) -o -name orange\*
  • 1
    does this mean that find doesn't distinguish between test or action tokens? and simply looks at whether the operand evaluates true or false in the same way test would in a shell script? – the_velour_fog Aug 6 '16 at 10:41
  • 3
    @the_velour_fog that's right; in fact actions also return true or false depending on whether they succeed. – Stephen Kitt Aug 6 '16 at 12:25
  • ah thats what I struggled to understand, I always assumed that find would have treated test and action primaries differently, the way a compiler would recognise and treat variable types like array, int and string differently. but you really need to treat find like its a little programming language and manage the operators and operands yourself, thanks – the_velour_fog Aug 6 '16 at 12:36
  • 2
    @the_velour_fog, from Unix Power Tools, 3rd Edition: "find's business is evaluating expressions - not locating files. Yes, find certainly locates files; but that's really just a side effect. For me, understanding this point was the conceptual breakthrough that made find much more useful." – Wildcard Sep 28 '16 at 20:05
  • @wildcard, yes getting that its really a conditional expression evaluator is important. as per your question - and my challenge - was how do the rules work. comparing the find command to a shell conditional expression (although much more complicated than normal) is what my breakthrough was with find. It also helped with my general programming too. – the_velour_fog Sep 28 '16 at 20:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.