perldiag2

Under Unix, this error is usually caused by executing Perl code -- either the main program, a module, or an eval'd string -- that was transferred over a network connection from a non-Unix system without properly converting the text file format.

Under systems that use something other than '\n' to delimit lines of text, this error can also be caused by reading Perl code from a file handle that is in binary mode (as set by the binmode operator).

In either case, the Perl code in question will probably need to be converted with something like s/\x0D\x0A?/\n/g before it can be executed.

    sub mod { $_[0] = 1 }
    mod(2);

Another way is to assign to a substr() that's off the end of the string.

Note, however, that the minimal matching quantifiers, *?, +?, and ?? appear to be nested quantifiers, but aren't. See the perlre manpage.

One possible cause for this is that you expected to have imported a constant to your name space with use or import while no such importing took place, it may for example be that your operating system does not support that particular constant. Hopefully you did use an explicit import list for the constants you expect to see, please see use and import. While an explicit import list would probably have caught this error earlier it naturally does not remedy the fact that your operating system still does not support that constant. Maybe you have a typo in the constants of the symbol import list of use or import or in the constant name at the line where this error was triggered?

The request was judged to be small, so the possibility to trap it depends on the way perl was compiled. By default it is not trappable. However, if compiled for this, Perl may use the contents of $^M as an emergency pool after die()ing with this message. In this case the error is trappable once.

    my $foo, $bar = @_;

when you meant

    my ($foo, $bar) = @_;

Remember that ``my'' and ``local'' bind closer than comma.

You probably wrote something like this:

    @list = qw(
        a # a comment
        b # another comment
    );

when you should have written this:

    @list = qw(
        a
        b
    );

If you really want comments, build your list the old-fashioned way, with quotes and commas:

    @list = (
        'a',    # a comment
        'b',    # another comment
    );

You probably wrote something like this:

    qw! a, b, c !;

which puts literal commas into some of the list items. Write it without commas if you don't want them to appear in your data:

    qw! a b c !;

    open FOO || die;

is now misinterpreted as

    open(FOO || die);

because of the strict regularization of Perl 5's grammar into unary and list operators. (The old open was a little of both.) You must put parentheses around the filehandle, or use the new ``or'' operator instead of ``||''.

    open FOO || die;

    %hash = { one => 1, two => 2, };    # WRONG
    %hash = [ qw/ an anon array / ];    # WRONG
    %hash = ( one => 1, two => 2, );    # right
    %hash = qw( one 1 two 2 );                  # also fine

On the other hand, if you were actually hoping to treat the array element as a list, you need to look into how references work, because Perl will not magically convert between scalars and lists for you. See the perlref manpage.

On the other hand, if you were actually hoping to treat the hash element as a list, you need to look into how references work, because Perl will not magically convert between scalars and lists for you. See the perlref manpage.

This is a CGI error, not a Perl error.

You need to make sure your script is executable, is accessible by the user CGI is running the script under (which is probably not the user account you tested it under), does not rely on any environment variables (like PATH) from the user it isn't running under, and isn't in a location where the CGI server can't find it, basically, more or less. Please see the following for more information:

        http://www.perl.com/perl/faq/idiots-guide.html
        http://www.perl.com/perl/faq/perl-cgi-faq.html
        ftp://rtfm.mit.edu/pub/usenet/news.answers/www/cgi-faq
        http://hoohoo.ncsa.uiuc.edu/cgi/interface.html
        http://www-genome.wi.mit.edu/WWW/faqs/www-security-faq.html

    {
        local $^W = 0;
        eval "sub name { ... }";
    }

    A keyword is misspelled.
    A semicolon is missing.
    A comma is missing.
    An opening or closing parenthesis is missing.
    An opening or closing brace is missing.
    A closing quote is missing.

Often there will be another error message associated with the syntax error giving more information. (Sometimes it helps to turn on -w.) The error message itself often tells you where it was in the line when it decided to give up. Sometimes the actual error is several tokens before this, because Perl is good at understanding random input. Occasionally the line number may be misleading, and once in a blue moon the only way to figure out what's triggering the error is to call perl -c repeatedly, chopping away half the program each time to see if the error went away. Sort of the cybernetic version of 20 questions.

    $[ = 0;
    $[ = 1;
    ...
    local $[ = 0;
    local $[ = 1;
    ...

This is to prevent the problem of one module changing the array base out from under another module inadvertently. See perlman:perlvar.

If the Perl script is being executed as a command using the #! mechanism (or its local equivalent), this error can usually be fixed by editing the #! line so that the -T option is a part of Perl's first argument: e.g. change perl -n -T to perl -T -n.

If the Perl script is being executed as perl scriptname, then the -T option must appear on the command line: perl -T scriptname.