Re: "find" ends with exit code "0" although exec command returned an error

[Bernhard Voelker]

On 10/04/2015 06:46 PM, Thomas D. wrote:
> Hi,
> 
> for me it looks like "find" returns an invalid exit code when "-exec"
> returns an error:
> 
> $ mkdir /tmp/find-test
> $ touch /tmp/find-test/scripts{1..10}.sh
> $ touch /tmp/find-test/text{1..10}.txt
> $ find /tmp/find-test -name '*.sh' -exec chmod 755 \; \
>   && echo "find succeed" || echo "find failed"
> 
> Yes, I am missing the "{}" but that's how I encounter the bug.
> Output:
> 
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> chmod: missing operand after ‘755’
>> Try 'chmod --help' for more information.
>> find succeed
> 
> I expected "find failed" ("find" should have ended with non-zero exit code).
> 
> And yes, "chmod 755" returns an error:
> 
> $ chmod 755
> chmod: missing operand after ‘755’
> Try 'chmod --help' for more information.
> $ echo $?
> 1
> 
> 
> 
> $ find -version
> find (GNU findutils) 4.5.14
> Packaged by Gentoo (4.5.14-r1)
> Copyright (C) 2014 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>.
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.

Thanks for the report, however, although the result may be surprising a bit,
I think it is mandated by POSIX:

  http://pubs.opengroup.org/onlinepubs/9699919799/utilities/find.html

  If the primary expression is punctuated by a <semicolon>, the utility
  utility_name shall be invoked once for each pathname and the primary
  shall evaluate as true if the utility returns a zero value as exit
  status.
  [...]

  If the primary expression is punctuated by a <plus-sign>, [...]. If any
  invocation returns a non-zero value as exit status, the find utility shall
  return a non-zero exit status.


You see, there's that subtle difference between "find -exec ... \;" and
"find -exec ... +" which can be demonstrated like this:

  $ touch f

  $ find f -exec false '{}' \; ; echo $?
  0

  $ find f -exec false '{}' + ; echo $?
  1

That behaviour is somehow documented in the manpage, yet it could be
more explicit - especially the difference between the return value of
an expression and the exit code of find in general.  E.g. the following
demonstrates that by having a 2nd -exec expression which whitnesses the
return value of the first one:

  $ find /bin/true -exec env '{}' \; -exec echo 'file {}: 1st exec returned 
true' \; ; echo $?
  file /bin/true: 1st exec returned true
  0

  $ find /bin/false -exec env '{}' \; -exec echo 'file {}: 1st exec returned 
true' \; ; echo $?
  0

Of course, the return value of the expression does not affect the
exit value in the above example due to the "-exec ... \;", while it
would have with the "-exec ... +" syntax.

Have a nice day,
Berny