putenv(3C)          (C Programming Language Utilities)           putenv(3C)


   NAME
         putenv - change or add value to environment

   SYNOPSIS
         #include <stdlib.h>

         int putenv (char *string);

   DESCRIPTION
         string points to a string of the form ``name=value.''  putenv makes
         the value of the environment variable name equal to value by altering
         an existing variable or creating a new one.  In either case, the
         string pointed to by string becomes part of the environment, so
         altering the string will change the environment.  The space used by
         string is no longer used once a new string-defining name is passed to
         putenv.  Because of this limitation, string should be declared static
         if it is declared within a function.

   SEE ALSO
         exec(2), getenv(3C), malloc(3C), environ(5).

   DIAGNOSTICS
         putenv returns non-zero if it was unable to obtain enough space via
         malloc for an expanded environment, otherwise zero.

   NOTES
         putenv manipulates the environment pointed to by environ, and can be
         used in conjunction with getenv.  However, envp (the third argument
         to main) is not changed.
         This routine uses malloc(3C) to enlarge the environment.
         After putenv is called, environmental variables are not in
         alphabetical order.  A potential error is to call the function putenv
         with a pointer to an automatic variable as the argument and to then
         exit the calling function while string is still part of the
         environment.


















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