Hi,
I'd like to discuss an idea of more dynamic argv manipulation.
Since execline heavily relies on chain loading it becomes very
important whether block is executed directly or via fork; add to that
extreme importance of ENV vars as a way to carry state through chain
loading and it becomes extremely painful at a times and leads to more
verbose code.
What if new `ifthen` commands was manipulating argv ? For instance
this code would be possible then
```
ifthen { s6-test -n ${DISCARD_ENV} }
{
exec -c
}
prog1
```
then instead of exec`ing into one or another it would compose argv
dynamically and execute into it:
true case:
[ "exec", "-c", "prog1", ....]
false case:
[ "prog1", ...]
with such class of commands it would be easier to compose optional bits of code
What do you think?
