${parameter}
...
If the first character of parameter is an exclamation point (!), and parameter is not a nameref, it intro‐
duces a level of indirection. Bash uses the value formed by expanding the rest of parameter as the new pa‐
rameter; this is then expanded and that value is used in the rest of the expansion, rather than the expansion
of the original parameter. This is known as indirect expansion.
[^] # Re: Double substitution en Bash
Posté par vmagnin (site web personnel, Mastodon) . En réponse au journal Courses Assistées par Ordinateur (CAO). Évalué à 2. Dernière modification le 27 avril 2020 à 19:11.
J'ai trouvé dans
man bash:${parameter}
...
If the first character of parameter is an exclamation point (!), and parameter is not a nameref, it intro‐
duces a level of indirection. Bash uses the value formed by expanding the rest of parameter as the new pa‐
rameter; this is then expanded and that value is used in the rest of the expansion, rather than the expansion
of the original parameter. This is known as indirect expansion.