possible wrong behaviour with patterns double [ with no closing ]

[Christoph Anton Mitterer <calestyo@xxxxxxxxxxxx>]

Hey.


Assuming a pattern of:
[.*^\]
my understanding was that this would actually mean:
- the literal string [. followed by
- the pattern notation special character * (i.e. any string) followed by
- the literal string ^]

Because ] is escaped, it's to be taken literally and in a pattern a [
without corresponding ] is to be taken literally as well.

That seems to work in dash:
$ case '[.^]' in ([.*^\]) echo match;; (*) echo no match;; esac
match
$ case '[.x^]' in ([.*^\]) echo match;; (*) echo no match;; esac
match
$ case '[.xx^]' in ([.*^\]) echo match;; (*) echo no match;; esac
match


However, adding another [ to the pattern:
[.*^[\]
which should be:
- the literal string [. followed by
- the pattern notation special character * (i.e. any string) followed by
- the literal string ^[]

No longer matches:
$ case '[.^[]' in ([.*^[\]) echo match;; (*) echo no match;; esac
no match
$ case '[.x^[]' in ([.*^[\]) echo match;; (*) echo no match;; esac
no match
$ case '[.xx^[]' in ([.*^[\]) echo match;; (*) echo no match;; esac
no match


Whereas, AFAIU POSIX, it should.

This works, btw. in bash, but neither in busybox sh, nor klibc sh.


Cheers,
Chris.