If your OS supports it you could use either a named pipe (see your system's mknod(1) man page); or if it has the support for named file descriptors use a pipe pair and tell it to read from /dev/fd/# (replacing the # with whatever fileno returns for the reader side; see perlipc for more on pipes). Then again it's possible that sqldr wants a seekable file and neither of these approaches will work and you'll be stuck with a temp file.