Bash has a bug: ${+} is syntactically invalid, as evidenced by the error
message when running the script, yet using 'set -n' was not able to flag
it as an error.
$ echo $BASH_VERSION
4.2.8(1)-release
$ bash -c 'echo ${+}'; echo $?
bash: ${+}: bad substitution
1
$ bash -cn '${+}'; echo $?
0
$ ksh -cn '${+}'; echo $?
ksh: syntax error at line 1: `+' unexpected
3
Meanwhile, a feature request: since $+ outputs a literal "$+", it is
proof that + cannot be a valid variable name. Bash should follow ksh'
lead by having 'set -n' warn about suspicious but usable constructs, at
least when --posix is not in effect.
$ bash -c 'echo $+'
$+
$ bash -cn '$+'; echo $?
0
$ ksh -cn '$+'; echo $?
ksh: warning: line 1: $ not preceded by \
0
--
Eric Blake ebl...@redhat.com +1-801-349-2682
Libvirt virtualization library http://libvirt.org
signature.asc
Description: OpenPGP digital signature
