.TH LIBENV_SELECT_VARIABLE_LIST 3 libenv
.SH NAME
libenv_select_variable_list - Keep wanted environment variables

.SH SYNOPSIS
.nf
#include <libenv.h>

size_t libenv_select_variable_list(const char **\fIvariables\fP, /* enum libenv_class */ ... /*, LIBENV_END */);
size_t libenv_vselect_variable_list(const char **\fIvariables\fP, va_list \fIclasses\fP);
size_t libenv_select_variable_list_with_dealloc(char **\fIvariables\fP, /* enum libenv_class */ ... /*, LIBENV_END */);
size_t libenv_vselect_variable_list_with_dealloc(char **\fIvariables\fP, va_list \fIclasses\fP);
.fi
.PP
Link with
.IR -lenv .

.SH DESCRIPTION
The
.BR libenv_select_variable_list ()
function removes elements in
.I variables
that match the name, optionally with an equals sign
.RB ( = )
followed by anything, of an environment variable that
do not belong to any of the environment variable classes
listed after the
.I variables
argument. The list must end with
.I LIBENV_END
to signal to the function that there are no
more arguments to read.
.PP
.I variables
should be a
.I NULL
terminated list, but may be
.IR NULL .
.PP
The
.BR libenv_select_variable_list_with_dealloc ()
function is a variant of the
.BR libenv_select_variable_list ()
function that deallocates, using the
.BR free (3)
function, any removed element.
.PP
The
.BR libenv_vselect_variable_list ()
and
.BR libenv_vselect_variable_list_with_dealloc ()
functions are variants of the
.BR libenv_select_variable_list ()
and
.BR libenv_select_variable_list_with_dealloc ()
functions, respectively, that use
.I va_list
instead of being properly variadic.

.SH RETURN VALUE
The
.BR libenv_select_variable_list (),
.BR libenv_vselect_variable_list (),
.BR libenv_select_variable_list_with_dealloc (),
and
.BR libenv_vselect_variable_list_with_dealloc ()
functions return the new number of elements in
.IR variables ,
excluding the
.I NULL
element at the end of the list.
The functions return 0 if
.I variables
is
.IR NULL .

.SH ERRORS
None.

.SH SEE ALSO
.BR libenv (7),
.BR enum_libenv_class (3),
.BR libenv_select_name_list (3),
.BR libenv_filter_variable_list (3).