Adding environ expansion it to existing options might break someone's setup if they already shared a folder with $ in the name. Maybe as a new option for root share?

Also just using $HOME is not enough to find home. Python will read /etc/passwd to find home.

Extending root share would effectively satisfy this request. This would also allow read-only shares in the home folder with portable instance folders.

$ in paths is normally pretty uncommon. But full variable expansion isn't necessary. Just the common ~, HOME, XDG_* at the beginning of the path would be sufficient.

Would also be useful to extend with following features:

• Ability to create folders that don't already exist, including random/temp folders
• Ability to map differently named folders
• Delete the temp folder on exit

I believe some of the above are already provided by bwrap options. They would be useful to map commonly disposable locations, like ~/.cache/*, to newly created temporary folders in tmpfs, like /run/user/####.

I'm picturing a GUI that looks like a table, with entry fields and checkboxes:

   SRC          DST          RO   VE   TMP
X  __________   __________   []   []   []
X  __________   __________   []   []   []
X  __________   __________   []   []   []

Also just using $HOME is not enough to find home. Python will read /etc/passwd to find home.

If you allow full variable expansion, wouldn't os.path.expandvars take care of $HOME?

I'm fine with dropping ~ if checking for it makes code too convoluted.

Kind of reminds me of a volume system that docker/podman used. It has been already been discussed in #56 .

As for expanding variables for paths. Only as a new option. Backwards compatibility is very important.

As for expanding variables for paths. Only as a new option. Backwards compatibility is very important.

That would be fine with me.

Backwards compatibility is very important.

What about a new share system that stores paths in the toml as lists? As long as new options are added only to the end of the list, backwards compatibility can be maintained with future expansions. (Extra or missing options can be ignored.)

[map_share]
map_paths = [
    ["SRC", "DST", RO, VE, TMP, ETC],
]