putenv

   Change or add a name-value pair to the environment.

Syntax

   (on unix systems, it is usually defined in:  #include <stdlib.h> )
   extern int  putenv ( char* name_value );

Parameters

   name_value  string in one of the following 2 forms:
                  name           to remove the name variable
                  name=value     to assign a value to the name variable

Return Values

   0           Success in the name variable removal, change, or addition.

   ENOENT      name variable not found in the environment to remove.

   ERANGE      value for JCW name not in range of 0..65535.

   EINVAL      Invalid variable name.
               Read-only system variable name.
               Reserved name for JCW value (OK,WARN,FATAL,SYSTEM).
               Invalid integer value for system JCW.

Description

   The putenv function performs one of 2 functions depending on the form
   of the given string value. When only a variable name is given, the
   variable is removed from the environment. Otherwise, if the variable
   does not exist, it is created; then assigned the value part which
   follows the "=" assignment char.

   Unlike unix systems, the MPE/iX environment for variables is globally
   defined for the Session or Job. It is not unique per process.
   Therefore the name_value string can be a literal and is not used as
   part of the environment strings.

   name variables must follow the rules of MPE/iX variable names.

   values can be integer, boolean: TRUE FALSE, or string. When they are
   placed into the environment, their value types are set to integer,
   boolean, or string.

Examples

   #define  _MPEXL_SOURCE
   #include <stdio.h>         /* printf   */
   #include <string.h>        /* strerror */
   #include <errno.h>         /* errno, _mpe_status */

   int main ()
   {
      int   x;

      x = putenv ( "JCW=2" );             /* set system JCW value */

      x = putenv ( "MYVAR=some value" );  /* create MYVAR */

      printf ( "putenv=%d  errno %d %s   mpestat %d:%d\n",
         x, errno, strerror ( errno ),
         _mpe_status.decode.error_num, _mpe_status.decode.subsys_num );

      x = putenv ( "MYVAR" );             /* delete MYVAR */
   }

See Also

   getenv(), intrinsics HPCIDELETEVAR, HPCIPUTVAR, HPCIGETVAR

Author: Keven Miller 05/01/2011