Function getoutput 

pub fn getoutput(cmd: &str, qt: i32) -> Option<Vec<String>>

Port of LinkList getoutput(char *cmd, int qt) from Src/exec.c:4712-4791. Runs a command-substitution body in the active executor, then routes the captured stdout through readoutput(pipe, qt, NULL) semantics at c:4855-4872.

C return shape: LinkList of char*. Rust port returns Vec<String> (same shape, owned).

qt matches C exactly:

• qt=1 (quoted, "$(...)"): trim trailing newlines, return entire output as a single-element vec. C c:4858-4862: if output empty, returns a single Nularg sentinel so callers see “empty value” rather than “no value”.
• qt=0 (unquoted, $(...)): trim trailing newlines, then spacesplit(buf, allownull=false) per c:4865-4871, and shtokenize each word when GLOBSUBST is set (c:4868-4869) so the substituted words glob downstream.

Both arms — $(< file) (c:4746) and $( cmd ) (c:4772) — go through the same c:4858-4872 tail (inlined twice — see the cross-reference notes at :619 and :3829), mirroring C where both go through readoutput.

Uses with_executor (panics on missing VM context), not try_with_executor + unwrap_or_default(). C getoutput calls execpline directly — there’s no “no shell” code path. The silent-no-op pattern (return empty string when no executor) would mask catastrophic state corruption as “command produced no output”, which is the failure mode the subst.rs:496 warning block flags. Port of getoutput() from Src/exec.c:4713 — C decl getoutput(char *cmd, int qt). getoutput — see implementation.