The error is not passed as an argument to your die handler, but is in $@.

How so? $@ is the last eval error. The arguments to die are passed to the DIE handler (whether invoked by perl itself or via die): 

local $SIG{__DIE__} = sub {
    open my $fh, '>>', 'log.err'
        or warn "Can't append to 'log.err': $!" and return;
    print $fh @_, "\n\$\@: |$@|";
};
eval { die "fubar!"; }; # <--- update, semicolon was missing
1 / 0;
__END__
Illegal division by zero at foo.pl line 8.

[download]

Contents of log.err:

@_: |fubar! at foo.pl line 7.
|
$@: ||
@_: |Illegal division by zero at foo.pl line 8.
|
$@: |fubar! at foo.pl line 7.
|

[download]

The fubar! at foo.pl line 7. is repeated since $@ hasn't been cleared. If there had been a subsequent succeeding eval, $@ had been cleared.

Neither die messages nor system errors ($!) are shoehorned into $@ for the DIE handler.

update 2:

Also, your __DIE__ handler will also be invoked from within eval { ... } blocks, which is most likely only confusing to you. You should check $^S to see if eval is currently running: 
    return if $^S; # we are within an eval block

[download]

This, as a general advice, is misleading. One might very well be interested in eval errors.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In reply to Re^2: how i capture a script error to a file ? by shmem
in thread how i capture a script error to a file ? by gabrielsousa

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.