Parameter expansion on multiple variables

Question

Parameter expansion on a single variable works as expected. But how to expand parameters that comprise several variables? Example:

#!/bin/sh

foo=/lorem/ipsum; bar=dolor/sit

tmp="$foo/$bar"
printf '%s\n' "${tmp%/*}"

How to run this parameter expansion without the need of the temporary variable?

Answer 1

Expansion allows for only the one variable, necessitating the temp var. However, if this is the exact use case, dirname may work for you, since it does pretty much exactly the same thing as %/*:

$ foo=/lorem/ipsum; bar=dolor/sit
$ dirname $foo/$bar
/lorem/ipsum/dolor

Answer 2

Here's one ... workaround ... that does not set the temporary variable in the current shell:

foo=/lorem/ipsum; bar=dolor/sit
(tmp="$foo/$bar"; printf '%s\n' "${tmp%/*}")