Clarify /tmp use

[0xmichalis]

Is it necessary to use /tmp for downloading txhashsets?

See https://www.grin-forum.org/t/chain-building-stuck-at-58/4553 for more info

[antiochp]

Related - #2685

There is no specific reason we went with $TMPDIR beyond using a standard location. But as mentioned in the forum we have some fairly specific disk space requirements so want to ensure we use a disk with sufficient space.

It sounds like we may want to consider using a grin specific tmp dir under ~/home/.grin/main or something similar?

I do think we need to segregate the sandbox_dir and/or tmpdir from our mainnet/floonet chain_data or chain_data/txhashset dirs.

[0xmichalis]

At a minimum we should document this somewhere prominently.

[garyyu]

Interesting!
Agree to use a grin specific tmp dir under ~/.grin/main/tmp for mainnet and ~/.grin/floo/tmp for floonet.
Also a specific sandbox dir under ~/.grin/main/tmp/txhashset.

It deserve a dedicated PR to fix all these folder name / location issues. And let #2685 purely only for the sandbox fixing.

[0xmichalis]

Fixed by #2772