Essentially this means that any file stored in /tmp is actually being stored in memory rather than on your persistent storage devices. Before starting, it is worth explaining that: Accessing content from RAM is much faster than the fastest SSDs in terms of both latency and throughput/bandwidth.

Where is tmp stored?

The TMP folder holds any files an application uses during an installation or removal process. The folder also stores any files an application uses on a temporary basis. Temporary files are also stored in the hidden “/var/TMP” folder, also located in the root directory.

Does tmp exist?

In practice, /tmp is pretty much guaranteed to exist. However, even if it exists, that doesn’t mean you should put temporary files there. The standard convention is to use the TMPDIR environment variable. If it exists, it points to a directory for temporary files.