acme: execute "hard" runs in $SHELL when available.

[marius.eriksen, 2012-10-07 04:23:07]

This is mostly an RFC: it does create issues with quoting inconsistency with
quoting. Eg. when using bash, 2-clicking:

  echo "hello, world"

produces

  "hello, world"

since that doesn't trigger the "hard" rule, but:

  echo "hello world" 2>/dev/null

yields

  hello, world

since it does.

One possible solution is to have the shell execute everything.

[rsc, 2012-10-07 14:01:34]

For better or worse acme's execution model hard-codes rc's behavior,
so that's the shell that gets used, always. I don't think I'd want to
change this. I use SHELL=bash (it's too hard not to in some
environments) but still expect acme commands to be run by rc. However,
I also understand that it's inconvenient to be forced to use a
specific shell.

I would be willing to go along with something like this if instead we
use a separate environment variable $acmeshell. If that is set, then
the shell gets used for everything (early goto hard).

Russ

[marius.eriksen, 2012-10-07 21:11:29]

That makes sense.

[rsc, 2012-10-21 20:52:13]

LGTM

[rsc, 2012-10-21 20:52:13]

*** Submitted as http://code.google.com/p/plan9port/source/detail?r=dfcebf03fe71
***

acme: add $acmeshell to control execution shell

R=rsc
CC=plan9port.codebot
http://codereview.appspot.com/6614056

Committer: Russ Cox <rsc@swtch.com>