Jon Seymour <jon.seym...@gmail.com> wrote:
> The manual specifies a rule for ${parameter:+word}, but not
> ${parameter+word}.
It's there, but easy to miss:
In each of the cases below, word is subject to tilde expansion, parame-
ter expansion, command substitution, and arithmetic expansion. When
not performing substring expansion, bash tests for a parameter that is
unset or null; omitting the colon results in a test only for a parame-
ter that is unset.
paul
