Exec: reaching into a box

dabs exec is the single reach-in verb. The -- separator picks the form.

Screens verified by tests/test_exec.py.

Shell form (no `--`)

Tokens are joined into one sh -c line inside the box — pipes, globs, and && work:

dabs exec sh-________ 'cd /work && echo *'

dabs.yaml  data

Everything after -- is an exact argv, no shell involved — nothing expands:

dabs exec sh-________ -- echo '*'

Use it when arguments must arrive untouched (paths with spaces, $ you don’t want expanded, program flags that look like dabs flags).

dabs sets DABS_NAME inside every box to the box’s instance name, so a program can detect it is sandboxed:

dabs exec sh-________ 'echo I am $DABS_NAME'

I am shell-____________

Any unambiguous prefix of a node id (or instance name) resolves, git-style. A name that matches nothing is a clean error:

dabs: no box matches "nothere" (see dabs ls)

A name matching more than one box is refused too — dabs never guesses which box you meant. Disambiguate with more characters, from dabs ls.