error report

steph_bow has asked for the wisdom of the Perl Monks concerning the following question:

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Re: error report by TOD (Friar) on Mar 06, 2008 at 10:12 UTC
try something like this: `use Symbol 'gensym'; our $log = gensym; open $log, ">/path/to/logfile" or die $!; our $DEBUG = 1; sub add_log; local $SIG{__WARN__} = sub { &add_log(shift) }; local $SIG{__DIE__} = sub { &add_log(shift); exit 1 }; sub add_log { print $log, shift(); flush $log if $DEBUG; } sub DESTROY { close $log; }` [download] admitted this is more of a rough draft, but the method should be clear from these few lines. -------------------------------- masses are the opiate for religion.	[reply] [d/l]
Re: error report by nefigah (Monk) on Mar 06, 2008 at 10:12 UTC
Since these messages are normally sent to STDERR, you can achieve this by redirecting STDERR to the text file of your choice. Check out http://perldoc.perl.org/functions/open.html, especially the part about halfway down that starts, "You may also, in the Bourne shell tradition, specify an EXPR beginning with..." Good luck!	[reply]
Re: error report by romandas (Pilgrim) on Mar 06, 2008 at 10:35 UTC
Besides redirecting to STDERR within the program, you can also redirect it from the shell if you run it at the commandline. In both Linux and Windows, you can do this: c:\perl_program.pl 2> error.log or $./perl_program 2> error.log This allows you to change the error file on the fly, or see it onscreen without changing the code. You can redirect STDOUT the same way, just leave off the 2 (or use 1; same thing).	[reply]
Re^2: error report by marc_ (Deacon) on Mar 06, 2008 at 20:03 UTC
If in a *nix or Cygwin environment I will usually "\| tee <filename>" which duplicates the output to both the console and the named file.	[reply]
Re: error report by sundialsvc4 (Abbot) on Mar 06, 2008 at 22:11 UTC
Note that in most (if not all) shells, using two greater-than signs (e.g. `>>filename`) will append the output to the specified file (or create it if it does not yet exist), whereas using only one such character will replace it. In Unix-ish environments, all programs have one “standard input” file (STDIN), one “standard output” (STDOUT), and one “ standard error-output” (STDERR). The default is that STDIN reads from the terminal (or from an input-pipe), and both STDOUT and STDERR write to the terminal.	[reply]


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