On Fri, 20 Aug 2021 19:28:25 +0000
hancooper via Bug reports for the GNU Bourne Again SHell <bug-bash@gnu.org>
wrote:
> I am using EPOCHREALTIME and then computing the corresponding human readable
> form, that can handle
> changes in locale
>
> now=$EPOCHREALTIME
> printf -v second '%(%S)T.%s' "${now%[^[:digit:]]*}" "${now#*[^[:digit:]]}"
> printf -v minute '%(%M)T' "${now%[^[:digit:]]*}"
> printf -v hour '%(%H)T' "${now%[^[:digit:]]*}"
>
> Incidentally, [![:digit:]] does not work there, you need to use the
> POSIX-specified caret (^) instead of an
> exclamation mark when using character classes. I'm not sure if this is
> intentional or a bug in bash; man
> page doesn't seem to mention it.
"If an open bracket introduces a bracket expression as in XBD RE Bracket
Expression, [...] the <exclamation-mark> character ( '!' ) shall replace the
<circumflex> character ( '^' ) in its role in a non-matching list in the
regular expression notation."
So says POSIX on the matter of pattern matching notation. In other words, only
the exclamation-mark is POSIX-specified, although bash happens to tolerate the
use of a circumflex, in which case it should behave in the exact same way. Are
you able to show a concrete example of one behaving differently from the other?
--
Kerin Millar
