NAME
   Env::C - Get/Set/Unset Environment Variables on the C level

SYNOPSIS
     use Env::C;

     my $key = "USER";
     $val = Env::C::getenv($key) || '';

     Env::C::setenv($key, "foobar", [$override]);
     $new_val = Env::C::getenv($key) || '';

     Env::C::unsetenv($key);

     my $ar_env = Env::C::getallenv();
     print join "\n", @$ar_env;

DESCRIPTION
   This module provides a Perl API for getenv(3), setenv(3) and
   unsetenv(3). It also can return all the "environ" variables.

   Sometimes Perl invokes modules with underlaying C APIs which rely on
   certain environment variables to be set, if these variables are set in
   Perl and the glue code doesn't worry to set them on the C level, these
   variables might not be seen by the C level. This module shows what
   really the C level sees.

 FUNCTIONS
   * getenv()
         $val = Env::C::getenv($key);

       Returns the value of the environment variable matching the key or
       "undef".

   * setenv()
         Env::C::setenv($key, $value, [$override]);

       The setenv() function adds the variable $key to the environment with
       the value $value, if $key does not already exist. If $key does exist
       in the environment, then its value is changed to $value if $override
       is non-zero; if $override is zero or is not passed, then the value
       of $key is not changed.

   * unsetenv()
         Env::C::unsetenv($key);

       The unsetenv() function deletes the variable $key from the
       environment.

   * getallenv()
         my $ar_env = Env::C::getallenv();
         print join "\n", @$ar_env;

       The getallenv() function returns an array reference which includes
       all the environment variables.

 EXPORT
   None.

Thread-safety and Thread-locality
   This module should not be used in the threaded enviroment.

   Thread-locality: the OS, which maintains the struct "environ", shares it
   between all threads in the process. So if you modify it in one thread,
   all other threads will see the new value. Something that will most
   likely break the code.

   This module is not thread-safe, since two threads may attempt to
   modify/read the struct "environ" at the same time. I could add locking
   if in threaded-environment. However since the lock can't be seen by
   other applications, they can still bypass it causing race condition. But
   since thread-locality is not maintained, making this module thread-safe
   is useless.

   If you need to modify the C level of %ENV for all threads to see, do
   that before threads are started. (e.g. for mod_perl 2.0, at the server
   startup).

AUTHOR
   Stas Bekman <[email protected]>

COPYRIGHT
   This is a free software; you can redistribute it and/or modify it under
   the terms of the Artistic License.

SEE ALSO
   perl.