@Override
	protected String toDSL() {
		String fileName = file.getName();
		return String.format("file --dir=%s --name=%s --suffix=%s --charset=%s --binary=%b --mode=%s",
				FixtureUtils.handleShellEscapeProcessing(file.getParent()),
				fileName.substring(0, fileName.lastIndexOf(".txt")), "txt", charset, binary, "APPEND");
	}
Wait at most {@code timeout} ms for the file to appear and return its contents.
spring-xd-test-fixtures/src/main/java/org/springframework/xd/test/fixtures/FileSink.java