On Sat, Mar 23, 2024, at 11:34 AM, A4-Tacks wrote: > Description: > I am unable to use logical inversion operators in line > arithmetic extensions, nor can I escape them, which is undoubtedly > abnormal > > Repeat-By: > ```bash > $ ((!RANDOM)) > bash: !RANDOM: event not found > ```
Unfortunately this is intentional and documented. In interactive shells with default settings, unquoted `!' introduces a history expansion [1]. You cannot backslash-escape `!' within `((exp))' because `exp' is treated almost [*] as if it were double-quoted, and within double quotes `\' escapes `!' but is not removed [3]. [1]: https://www.gnu.org/software/bash/manual/html_node/History-Interaction.html [2]: https://www.gnu.org/software/bash/manual/html_node/Conditional-Constructs.html [3]: https://www.gnu.org/software/bash/manual/html_node/Double-Quotes.html [*]: One exception is that double quotes themselves are removed, so another (arguably worse) workaround is `(("!"RANDOM))'. -- vq
