The /run directory is the companion directory to /var/run . Like for example /bin is the companion of /usr/bin .

What is in the run directory?

This directory contains system information data describing the system since it was booted. Files under this directory must be cleared (removed or truncated as appropriate) at the beginning of the boot process. The purposes of this directory were once served by /var/run .

What is run used for in Linux?

/run is the “early bird” equivalent to /var/run , in that it’s meant for system daemons that start very early on (e.g. systemd and udev ) to store temporary runtime files like PID files and communication socket endpoints, while /var/run would be used by late-starting daemons (e.g. sshd and Apache).