Read-only clients like unifyfs-ls will write out a spill over file at the end of execution.
A temporary fix is to set both UNIFYFS_LOGIO_SPILL_SIZE and UNIFYFS_LOGIO_SHMEM_SIZE to 0 before running the read-only client.
Or maybe we can add a read-only mode of initialization, so the read-only clients can configure all parameters programmatically.