putenv(3C)                                             putenv(3C)



NAME
     putenv - changes existing environmental variable  values  or
     adds new ones

SYNOPSIS
     int putenv(string)
     char *string;

DESCRIPTION
     putenv is a function that makes the value of the environment
     variable name equal to value by altering an existing
     variable or creating a new one.  The input parameter string
     points to a string that has the form

        name = value

     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 argument is passed to
     putenv.

STATUS MESSAGES AND VALUES
     The putenv function returns a nonzero value if it was unable
     to obtain enough space by means of malloc for an expanded
     environment; otherwise, putenv returns zero.

WARNINGS
     The putenv function 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, environment variables are not in
     alphabetical order.

     An error may result if you call putenv with an automatic
     variable as the argument, then exit the calling function
     while string is still part of the environment.

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












January 1992                                                    1