/run runtime data

The /run directory is used by system packages to store small amounts of runtime data (such as socket files). It is a tmpfs file system, and is writable only by privileged programs.

The /run/log directory can be used by system components to store logs in, either before being written out to /var/log or before the /var/log file system is available.

The /run/user/ path contains per-user runtime directories. By default, these will be individual tmpfs file systems mounted by systemd when the user logs in, and erased when the user is no longer logged in. As per the XDG Base Directory Specification, these paths should not be referenced directly but rather via the $XDG_RUNTIME_DIR environment variable.