These are sent to QEMU as double-quoted strings (the single-quoted JSON is
parsed to get interpolation and printed back; commit 563890c7c7, "libqtest:
escape strings in QMP commands, fix leak", 2014-07-01). However, doing the
interpolation requires a parser that recognizes the single-quoted strings.
IMHO this is the wrong solution to the problem. Consider the equivalent
libvirt code that uses a standard JSON library underneath and has a high
level API to serialize args into the command
qemuMonitorJSONMakeCommand("qom-get",
"s:path", id,
"s:property", "temperature");
Of course this example is reasonably easy since it is a flat set of
arguments. Nested args get slightly more complicated, but still always
preferrable to doing string interpolation IMHO.