Is by default /tmp folder mounted on ram in dietpi? Is I am allowed to use this location for non critical files like plex transcoding etc. if it is allowed what will be the bash file command to delete those files periodically to regain storage. i also want to divert homeassistant log file on ram so that it reduce writing on sd card. the logs from my homeassistant are not critical, only i want whenever system restart the history file start from that event without error. i do not need previous history. something like this in configration.yml "Recorder - Home Assistant "
i already diverted plex transcode folder in that direction. i think it is working perfectly like this photo.
You can store there anything that is not important to survive a reboot or power loss.
There is no specific bash command to delete files periodically, but you could try something like this: https://tecadmin.net/delete-files-older-x-days/
Normally logs are rotated with logrotation to save space, but this would require you to install the utility.
Whether it is sufficiently large (respectively your physical RAM size is) to hold HD/UHD video transcodings, at all or without triggering regular swap file usage, is a different question . By default those are stored to disk. But with sufficient RAM of course it is a great idea to do all that in RAM, also to avoid disk I/O bottlenecks. You may need to raise the /tmp tmpfs size then. You can edit /etc/fstab, the /tmp line size= option, then run mount -o remount /tmp to apply the change (contained data remains on such a remount).