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  • (1) I can’t reproduce the results you show in your first code block: declare name followed by declare -p name yields “bash: declare: name: not found”.  (Although declare -p | grep na yields declare -- name.) (2) I believe that it’s a little bit misleading to present echo "${name-isunset}" in the context of declare name, inasmuch as it treats an undeclared (i.e., undefined) variable the same as a declared but unset variable. (3) You might want to mention that namerefs are available only in bash version 4.3 and higher. Commented Jun 22, 2019 at 18:57
  • @G-Man Thank you for your remarks! I'll address them as soon as I can and I'll update my answer where appropriate. As for (1), my GNU bash, version 5.0.7(1)-release (x86_64-pc-linux-gnu) on Arch Linux still yields the results I showed. Maybe that behavior has been introduced only recently, I'll investigate that. Commented Jun 22, 2019 at 19:43
  • Yeah; I'm only using version 4.3. Commented Jun 22, 2019 at 20:12
  • 2
    @G-Man Answer updated with notes about (1) and (3). About (2): I aimed to illustrate that declare x doesn't set x, while declare x= does. I couldn't find any reference to back the assertion that declare -- x (as output of declare -p x) means "not set", while declare -- x="" means "set"; thus I brought in the ${parameter-word} expansion, even if it cannot discriminate between "unset" and "doesn't exist", as you point out. I'm not sure how can I clarify this in my answer (without distracting the reader from the point), though. Commented Jun 23, 2019 at 10:34
  • For (2), 1. If someone don't know what -- means since help declare doesn't show about that, in info bash it says "each builtin command documented as accepting options preceded by '-' accepts '--' to signify the end of the options". 2. The doc also says "If a variable name is followed by =VALUE, the value of the variable is set to VALUE" which may implicitly mean if not, then not set. Commented Jan 3 at 11:33