PUTENV(3C-SVR4)     RISC/os Reference Manual      PUTENV(3C-SVR4)



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 func-
     tion 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.


















                        Printed 11/19/92                   Page 1