unsetenv(3c) [opensolaris man page]

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)

UNSETENV(3P)						     POSIX Programmer's Manual						      UNSETENV(3P)

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

NAME

       unsetenv - remove an environment variable

SYNOPSIS

       #include <stdlib.h>

       int unsetenv(const char *name);

DESCRIPTION

       The unsetenv() function shall remove an environment variable from the environment of the calling process. The name  argument  points  to  a
       string,	which is the name of the variable to be removed. The named argument shall not contain an '=' character. If the named variable does
       not exist in the current environment, the environment shall be 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
       shall update the list of pointers to which environ points.

       The unsetenv() function need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.

RETURN VALUE

       Upon  successful  completion, zero shall be returned. Otherwise, -1 shall be returned, errno set to indicate the error, and the environment
       shall be unchanged.

ERRORS

       The unsetenv() function shall fail if:

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

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       Refer to the RATIONALE section in setenv().

FUTURE DIRECTIONS

       None.

SEE ALSO

       getenv(), setenv(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>, <sys/types.h>, <unistd.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and  the  original  IEEE
       and  The  Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003							      UNSETENV(3P)