setenv(3C)																setenv(3C)

NAME

       setenv(), unsetenv() - add, update or remove an environment variable

SYNOPSIS


   Parameters
	      envname	Points	to  a  string  containing  the	name of an environment variable to be added or altered.  This should not be a NULL
			pointer or null string, and the string should not contain an equal character.

	      envval	Points to a string containing the value to be set for the variable envname.

	      overwrite Indicates whether to overwrite the value of envname variable or not, if it already exists.  Expected values  are  non-zero
			and zero.  If the environment variable does not exist in the environment, then the value of this variable is ignored.

DESCRIPTION

       and functions update the environment of the calling process.

       If  envname  does  not  exist,  the function ignores the value of overwrite and adds the variable envname to the environment with the value
       envval.	If envname exists and overwrite is non-zero, then the variable envname is updated with the new value envval.   If  envname  exists
       and overwrite is zero, then the variable is not updated, and the function is considered to have completed successfully.

       The  function deletes the variable envname from the environment, if it exists.  If the envname variable does not exist in the current envi-
       ronment, 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 and is undefined.

EXTERNAL INFLUENCES

   Locale
       The category determines the interpretation of characters in string as single- and/or multi-byte characters.

   International Code Set Support
       Single- and multi-byte character code sets are supported.

RETURN VALUE

       The and functions return zero on success; otherwise they return and set to indicate the error.

ERRORS

       If the function fails, is set to one of the following values:

	      Sufficient memory is not available to add a variable or its value to
			     the environment.

	      The	     envname argument is a null pointer, points to an empty string, or points to a string containing an equal character.

       If the function fails, is set to the following value:

	      The	     envname argument is a null pointer, points to an empty string, or points to a string containing an equal character.

EXAMPLES

       The following code adds a new environment variable to the current environment.

       The following code updates the variable

       The following code removes the variable from the current environment.

WARNINGS

       The and functions manipulate the environment pointed to by environ, and can be used in conjunction with However, envp (the  third  argument
       to main) is not changed.

       The uses to enlarge the environment (see malloc(3C)).

       After the or function is called, environment variables may not be in alphabetical order.

AUTHOR

       and were developed by HP.

SEE ALSO

       exec(2), getenv(3C), malloc(3C), putenv(3C), environ(5), thread_safety(5).

STANDARDS CONFORMANCE

																	setenv(3C)