In list context, returns a (possibly empty) list of filename expansions on
the value of EXPR such as the standard Unix shell /bin/csh would do. In
scalar context, glob iterates through such filename expansions, returning
undef when the list is exhausted. This is the internal function
implementing the <*.c>
 operator, but you can use it directly. If
EXPR is omitted, $_
 is used.  The <*.c>
 operator is discussed in
more detail in I/O Operators in perlop.
Beginning with v5.6.0, this operator is implemented using the standard
File::Glob
 extension.  See File::Glob for details.