please set TMPDIR=/tmp when launching snaps

[Leo Arias]

After trying to snap an application that uses sqlite, following mhall's advice I had to add a wrapper that sets SQLITE_TMPDIR=/tmp. That is a simple workaround, but ugly. It will be better to set TMPDIR, and then sqlite will use that path with no additinal work.

From Jamie S:
Hmmm, we used to export TMPDIR but it seems that it was dropped when moving to
snap reexec. Can you file a bug so that sqlite users don't have to worry about
SQLITE_TMPDIR unless they want to?

[Michael Vogt (mvo)]

snap-confine sets up the private tmp and also sets: TMPDIR, TEMPDIR to /tmp.

[Michael Vogt (mvo)]

This is fixed:

$ snap run --shell test-snapd-tools.success
$ echo $SNAP
/snap/test-snapd-tools/3
$ echo $TMPDIR
/tmp