[Issue 15276] Allow specification of shell for spawnShell/executeShell/pipeShell

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15276

--- Comment #2 from github-bugzilla at puremagic.com ---
Commits pushed to master at https://github.com/D-Programming-Language/phobos

https://github.com/D-Programming-Language/phobos/commit/963f7e4170fd02aa07c95562f2554807a8fe9178
Issue 15276: Allow users to specify shell for executeShell, pipeShell,
spawnShell

This diff: This diff makes it possible to specify your preferred shell for the
various `*shell` functions in `std.process`. By default it uses the new
`nativeShell` function. `nativeShell` to always returns the native system shell
(see the "some history" section for why this is the default value). I chose to
create `nativeShell` rather than changeing `userShell` because I think it is
still valuable to have something like `userShell` around in Phobos.

The one part of this diff I'm not super thrilled by is the use of variadic
arguments (easier to see than to explain); if you have a suggestion for
something better I'd love to hear it :).

Note: The default shell is a breaking change for Windows, which probably
*should have* been broken same as posix in the diffs listed in the history
section below, but I suspect was overlooked. Find rationale behind making a
breaking change at all here: https://issues.dlang.org/show_bug.cgi?id=15000.

Some history:
https://github.com/D-Programming-Language/phobos/commit/a524a3571b18e440c4dd751fcf4e2d00b834fb22
and
https://github.com/D-Programming-Language/phobos/commit/f537cb50b5f8f9ad6d841db14b2e0a6cb845d008

Tried to move us from a world where we preferred the shell specified in the
SHELL environment variable to a world where we always went with the native
system shell, /bin/sh for posix. The former of those revisions was reverted in:
https://github.com/D-Programming-Language/phobos/commit/5b2b1fb59450cfc32ecec3252f543a9f6f34c2a4
Because the documentation was not updated to reflect the change.

Presently: we are in a state of schism, whereby `userShell` has behavior that
does not align with what is actually used in `executeShell`, `pipeShell`, and
`spawnShell`. This is something we *must* resolve.

Personal pain: This bit me when one of my scripts at work stopped working
because it dependend on features that don't exist in `sh` (but do in `bash`,
`zsh`, etc). It was really frustrating that there was no simple way to work
around this and specify my preferred shell; it is, of course, possible to
leverage the various `escape*` functions from `std.process` and `spawnProcess`
to use whichever shell I prefer, but this seems like something warranting first
class support. I was sad to not have something like this after a breaking
change.

https://github.com/D-Programming-Language/phobos/commit/9284ee864c38eb062a4bcd57b4a44556fe878b94
Merge pull request #3900 from markisaa/issue_15276

Issue 15276: Allow users to specify shell for executeShell, pipeShell,
spawnShell

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