Re: Suggestion: verbose option. Doc Update: -print and no action are NOT the same

[James Youngman]

On Mon, Mar 28, 2011 at 11:22 PM, Peggy Russell
<address@hidden> wrote:
> Hi,
>
> I have a suggestion and documentation update for `find`.
>
> The suggestion for findutils' find is to add a '-t, --verbose' or '--whatif' 
> option similar to the '-t' in `xargs`. At a minimum it would show what `find` 
> would generate, but it would not execute anything.  Note: The `-D exec` 
> option displayed no additional output.
>
> The documentation update is to add a paragraph describing that using the 
> default action of `-print` may NOT produce the same result as actually 
> supplying the action `-print` because of Boolean operator precedence.

The existing documentation says in the manpage:

       If the expression contains no actions other than -prune, -print is per‐
       formed on all files for which the expression is true.

And in the info documentation:

   You can omit the operator between two primaries; it defaults to
`-and'.  *Note Combining Primaries With Operators::, for ways to
connect primaries into more complex expressions.  If the expression
contains no actions other than `-prune', `-print' is performed on all
files for which the entire expression is true (*note Print File Name::).


The document doesn't state anywhere that the effect is the same as
adding -print on the end of the expressions (for exactly the reason
you state - the effect would not be the same).

Do you think this is unclear?

>
>  find -name tmp -prune -o -name \*.txt
>  find -name tmp -prune -o -name \*.txt -print
>
> The lack of an action in the first command means it is equivalent to:
>
>  find . \( -name tmp -prune -o -name \*.txt \) -print
>
> This causes tmp to be included in the output.  However for the second find 
> command the normal rules of Boolean operator precedence apply, so the pruned 
> directory does not appear in the output.
>
> As described here: http://content.hccfl.edu/pollock/unix/findcmd.htm
>
> Environment:
>  find --version
>  find (GNU findutils) 4.4.0
>
> Thank you.
> Peggy Russell
>
>