Re: ${var:+"quo ted"} and similar, inside unquoted here-docs

[Eric Blake]

[adding bug-bash]

On 08/29/2010 08:48 AM, Ralf Wildenhues wrote:
> With Solaris 10 sh (and others):
>
> cat<<EOF
> ${var-"quo  ted"}
> EOF
>
> "quo  ted"
>
> Whereas with bash (and others):
>
> quo  ted

Ouch.  New one to me.  ksh, zsh, and dash do not echo the quotes, so I'm 
thinking it may be a bash bug; hence the cc.

> Eric, did you have this in your recent autoconf.texi additions already?
> It can be a problem for all of the stuff that gets expanded into here
> documents.

Now, for the good news - the bug is easy to work around, while still 
using a here-doc.  A here-doc is parsed in a different context (no word 
splitting, no filename expansion) than normal, so /bin/sh does NOT have 
the bug related to "bad parameter" messages if you omit the quotes.

All shells that I had access to reliably gave the same output for:

cat <<EOF
${var-quo  ted}
EOF

quo  ted

--
Eric Blake   eblake@redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org