Re: Code obfuscation

[Lars Hecking]

John Poltorak writes:
> 
> Can anyone explain what this code in autoupdate does? :-
> 
> 
> my $macros = new Autom4te::XFile ("$autoconf"
>                . " --trace AU_DEFUN:'AU:\$f:\$1'"
>                . " --trace define:'AC:\$f:\$1'"
>                . " --melt /dev/null |");
 
 This is just one command, split over several lines for readability.
 The dot operator connects all these strings into one:

 $autoconf  --trace AU_DEFUN:'AU:\$f:\$1'  --trace define:'AC:\$f:\$1'  --melt 
/dev/null |"

 So, it runs the above command (everything before "|") and reads its output
 (the effect of the "|"). The /dev/null part specifies the input file
 $autoconf should read. $macros is a filehandle that is later read from,
 line by line.

 (I could be wrong, of course - I haven't familiarised myself with autoconf
  2 1/2 yet ;-)

> It appears to be causing the error msg:-
> 
> no such file or directory: /dev/null
> 
> on OS/2. This may be due to a bug in sh or Perl on OS/2 but it's difficult 
> to debug. What exactly is the purpose of '/dev/null |' above, and can I 
> try using something else instead just to get a pointer to the underlying 
> problem?

 Probably a bug in your sh.