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CGI::Compile(3pm) User Contributed Perl Documentation CGI::Compile(3pm)


CGI::Compile - Compile .cgi scripts to a code reference like ModPerl::Registry


  use CGI::Compile;
  my $sub = CGI::Compile->compile("/path/to/script.cgi");


CGI::Compile is a utility to compile CGI scripts into a code reference that can run many times on its own namespace, as long as the script is ready to run on a persistent environment.

NOTE: for best results, load CGI::Compile before any modules used by your CGIs.


Combined with CGI::Emulate::PSGI, your CGI script can be turned into a persistent PSGI application like:

  use CGI::Emulate::PSGI;
  use CGI::Compile;
  my $cgi_script = "/path/to/foo.cgi";
  my $sub = CGI::Compile->compile($cgi_script);
  my $app = CGI::Emulate::PSGI->handler($sub);
  # $app is a PSGI application


If your CGI script has a subroutine that references the lexical scope variable outside the subroutine, you'll see warnings such as:

  Variable "$q" is not available at ...
  Variable "$counter" will not stay shared at ...

This is due to the way this module compiles the whole script into a big "sub". To solve this, you have to update your code to pass around the lexical variables, or replace "my" with "our". See also <> for more details.



Does not need to be called, you only need to call it if you want to set your own "namespace_root" for the generated packages into which the CGIs are compiled into.

Otherwise you can just call "compile" as a class method and the object will be instantiated with a "namespace_root" of "CGI::Compile::ROOT".

You can also set "return_exit_val", see "RETURN CODE" for details.


    my $compiler = CGI::Compile->new(namespace_root => 'My::CGIs');
    my $cgi      = $compiler->compile('/var/www/cgi-bin/my.cgi');


Takes either a path to a perl CGI script or a source code and some other optional parameters and wraps it into a coderef for execution.

Can be called as either a class or instance method, see "new" above.


  • $cgi_script

    Path to perl CGI script file or a scalar reference that contains the source code of CGI script, required.

  • $package

    Optional, package to install the script into, defaults to the path parts of the script joined with "_", and all special characters converted to "_%2x", prepended with "CGI::Compile::ROOT::".







$cgi_script or $$code compiled to coderef.



Things like the query string and form data should generally be in the appropriate environment variables that things like CGI expect.

You can also pass arguments to the generated coderef, they will be locally aliased to @_ and @ARGV.

"BEGIN" and "END" blocks

"BEGIN" blocks are called once when the script is compiled. "END" blocks are called when the Perl interpreter is unloaded.

This may cause surprising effects. Suppose, for instance, a script that runs in a forking web server and is loaded in the parent process. "END" blocks will be called once for each worker process and another time for the parent process while "BEGIN" blocks are called only by the parent process.


The %SIG hash is preserved meaning the script can change signal handlers at will. The next invocation gets a pristine %SIG again.

"exit" and exceptions

Calls to "exit" are intercepted and converted into exceptions. When the script calls "exit 19" and exception is thrown and $@ contains a reference pointing to the array

    ["EXIT\n", 19]

Naturally, "$^S" in perlvar (exceptions being caught) is always "true" during script runtime.

If you really want to exit the process call "CORE::exit" or set $CGI::Compile::USE_REAL_EXIT to true before calling exit:

    $CGI::Compile::USE_REAL_EXIT = 1;
    exit 19;

Other exceptions are propagated out of the generated coderef. The coderef's caller is responsible to catch them or the process will exit.

Return Code

The generated coderef's exit value is either the parameter that was passed to "exit" or the value of the last statement of the script. The return code is converted into an integer.

On a 0 exit, the coderef will return 0.

On an explicit non-zero exit, by default an exception will be thrown of the form:

    exited nonzero: <n>

where "n" is the exit value.

This only happens for an actual call to "exit" in perfunc, not if the last statement value is non-zero, which will just be returned from the coderef.

If you would prefer that explicit non-zero exit values are returned, rather than thrown, pass:

    return_exit_val => 1

in your call to "new".

Alternately, you can change this behavior globally by setting:

    $CGI::Compile::RETURN_EXIT_VAL = 1;

Current Working Directory

If "CGI::Compile->compile" was passed a script file, the script's directory becomes the current working directory during the runtime of the script.

NOTE: to be able to switch back to the original directory, the compiled coderef must establish the current working directory. This operation may cause an additional flush operation on file handles.


These file handles are not touched by "CGI::Compile".

The "DATA" file handle

If the script reads from the "DATA" file handle, it reads the "__DATA__" section provided by the script just as a normal script would do. Note, however, that the file handle is a memory handle. So, "fileno DATA" will return "-1". integration

If the subroutine "CGI::initialize_globals" is defined at script runtime, it is called first thing by the compiled coderef.


These methods define some of the internal functionality of CGI::Compile and may be overloaded if you need to subclass this module.


Reads the source of a CGI script.



Path to the file the contents of which is to be read.



The contents of the file as a scalar string.


Creates a package name and coderef name into which the CGI coderef will be compiled into. The package name will be prepended with "$self-"{namespace_root}>.



The path to the CGI script file, the package name is generated based on this path.


  • $package

    The generated package name.

  • $subname

    The generated coderef name, based on the file name (without directory) of the CGI file path.


Takes the generated perl code, which is the contents of the CGI script and some other things we add to make everything work smoother, and returns the evaluated coderef.

Currently this is done by writing out the code to a temp file and reading it in with "do" in perlfunc so that there are no issues with lexical context or source filters.



The generated code that will make the coderef for the CGI.



The coderef that is the resulting of evaluating the generated perl code.


Tatsuhiko Miyagawa <>


Rafael Kitover <>

Hans Dieter Pearcey <>

kocoureasy <>

Torsten Foertsch <>

Joern Reder <>

Pavel Mateja <>

lestrrat <>


Copyright (c) 2020 Tatsuhiko Miyagawa <>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


ModPerl::RegistryCooker CGI::Emulate::PSGI

2020-08-04 perl v5.30.3