are
                     returned  by  readdir()  and so these predicates are faster to evaluate than predicates which need to stat the file first.  If you use the -fstype FOO predicate and specify a filesystem type FOO which is
                     not known (that is, present in ‘/etc/mtab’) at the time find starts, that predicate is equivalent to -false.

              3      At this optimisation level, the full cost‐based query optimiser is enabled.  The order of tests is modified so that cheap (i.e. fast) tests are performed first  and  more  expensive  ones  are  performed
                     later,  if  necessary.  Within each cost band, predicates are evaluated earlier or later according to whether they are likely to succeed or not.  For -o, predicates which are likely to succeed are evalu‐
                     ated earlier, and for -a, predicates which are likely to fail are evaluated earlier.

              The cost‐based optimiser has a fixed idea of how likely any given test is to succeed.  In some cases the probability takes account of the specific nature of the test (for example, -type f is assumed to be  more
              likely to succeed than -type c).  The cost‐based optimiser is currently being evaluated.  If it does not actually improve the performance of find, it will be removed again.  Conversely, optimisations that prove
              to  be  reliable,  robust  and  effective may be enabled at lower optimisation levels over time.  However, the default behaviour (i.e. optimisation level 1) will not be changed in the 4.3.x release series.  The
              findutils test suite runs all the tests on find at each optimisation level and ensures that the result is the same.

EXPRESSION
       The part of the command line after the list of starting points is the expression.  This is a kind of query specification describing how we match files and what we do with the files that were matched.  An expression is
       composed of a sequence of things:

       Tests  Tests return a true or false value, usually on the basis of some property of a file we are considering.  The -empty test for example is true only when the current file is empty.

       Actions
              Actions have side effects (such as printing something on the standard output) and return either true or false, usually based on whether or not they are successful.  The -print action for example prints the name
              of the current file on the standard output.

       Global options
              Global options affect the operation of tests and actions specified on any part of the command line.  Global options always return true.  The -depth option for example makes find traverse the file  system  in  a
              depth‐first order.

       Positional options
              Positional options affect only tests or actions which follow them.  Positional options always return true.  The -regextype option for example is positional, specifying the regular expression dialect for regular
              expressions occurring later on the command line.

       Operators
              Operators join together the other items within the expression.  They include for example -o (meaning logical OR) and -a (meaning logical AND).  Where an operator is missing, -a is assumed.

       The -print action is performed on all files for which the whole expression is true, unless it contains an action other than -prune or -quit.  Actions which inhibit the default -print are -delete, -exec, -execdir, -ok,
       -okdir, -fls, -fprint, -fprintf, -ls, -print and -printf.

       The -delete action also acts like an option (since it implies -depth).

   POSITIONAL OPTIONS
       Positional options always return true.  They affect only tests occurring later on the command line.

       -daystart
              Measure times (for -amin, -atime, -cmin, -ctime, -mmin, and -mtime) from the beginning of today rather than from 24 hours ago.  This option only affects tests