opensolaris man page for unsetenv

unsetenv(3C)						   Standard C Library Functions 					      unsetenv(3C)

NAME
       unsetenv - remove an environment variable

SYNOPSIS
       #include <stdlib.h>

       int unsetenv(const char *name);

DESCRIPTION
       The  unsetenv()	function removes an environment variable from the environment of the calling process. The name argument points to a string
       that is the name of the variable to be removed. The named argument cannot contain an '=' character. If the named variable does not exist in
       the current environment, the environment is unchanged and the function is considered to have completed successfully.

       If  the	application  modifies environ or the pointers to which it points, the behavior of unsetenv() is undefined. The unsetenv() function
       updates the list of pointers to which environ points.

RETURN VALUES
       Upon successful completion, 0 is returned. Otherwise, -1 is returned, errno set	to  indicate  the  error,  and	the  environment  is  left
       unchanged.

ERRORS
       The unsetenv() function will fail if:

       EINVAL	 The name argument is a null pointer, points to an empty string, or points to a string containing an '=' character.

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO
       getenv(3C), setenv(3C), attributes(5), standards(5)

SunOS 5.11							    1 Nov 2003							      unsetenv(3C)