mksh-current has just gained an experimental recursive parser for command substitutions, fixing RedHat BZ#496791 and decades-old complaints about the pdksh codebase, compared to AT&T ksh93. (GNU bash could also do the example, but not some other things mksh(1) parses fine now.)
This means that things like the following work now.
# POSIX, should “always” work echo $(case 1 in (1) echo yes;; (2) echo no;; esac) # POSIX optional, works now in mksh, works in GNU bash echo $(case 1 in 1) echo yes;; 2) echo no;; esac) # GNU bash seems to choke on comments ending with backslash # a comment with " ' \ x=$( echo yes # a comment with " ' \ ) # No non-recursive COMSUB parser can pass all of the above # tests and these below at the same time (some extensions) echo $(typeset -i10 x=16#20; echo $x) echo $(typeset -Uui16 x=16#$(id -u) ) . echo $(c=1; d=1 typeset -Uui16 a=36#foo; c=2 typeset -Uui16 b=36 #foo; d=2 echo $a $b $c $d) # the ‘#’ is especially tricky, that’s why the above cases
Next on my TODO is the complete rewrite of the read built-in command, as well as its documentation. I think that the (reduced) goals for mksh R40 will have been met by then, except porting to LynxOS and MPE, but we’re working on it, and re-testing Syllable and Plan 9). Of course, a release implies testing on a lot of the supposedly supported platforms, so it won’t be out “immediately”. Though, associative arrays have been removed from the R40 goals, so that I can at least get a new release out. Note that Debian and OpenSuSE Buildservice users have been provided with somewhat well-tested mksh-current snapshots for a while already, and Gentoo users can use the “live ebuild”; there’s always compiling from source too…