FW: Process substitution into loop

[Scott James Remnant]

Note the phrase *startup behaviour* in the paragraph - bash still supports
bashisms in its scripts when invoked as sh (after all, that's where the
entire historical problem with them comes from)

On Mon, Jun 13, 2011 at 4:56 PM, Grail Dane <grail69 at hotmail.com> wrote:

>  Hi James
>
> Thanks very much for the reply.  As you can probably guess the typo is in
> the email but not in
> the actual script.  I did further testing and as per the bash install
> instructions:
>
> *sh*
>
> A symlink to the *bash* program; when invoked as *sh*, *bash* tries to
> mimic the startup behavior of historical versions of *sh* as closely as
> possible, while conforming to the POSIX standard as well
>
>
>
> This would indicate that it is a bash builtin feature to use only POSIX
> compliant options.
> So from the Cookbook you may need to edit the following from the section
> you pointed me to:
>
> If you wish to change this, you can either make /bin/sh a symbolic link to
> your chosen shell
>
> As this does not work as expected in this case and it may be similar for
> other shells to.
>
> I will try the workaround of adding it as the default shell in the build
> and let you know how it goes :)
>
> Cheers
> grail
>
> > Date: Fri, 10 Jun 2011 11:22:12 +0100
> > From: james.hunt at ubuntu.com
>
> > To: grail69 at hotmail.com
> > CC: upstart-devel at lists.ubuntu.com
> > Subject: Re: Process substitution into loop
> >
> > Hi Grail,
> >
> > On 10/06/11 05:46, Grail Dane wrote:
> > >
> > >
> > >> Date: Thu, 9 Jun 2011 21:05:45 -0700
> > >> From: steve.langasek at ubuntu.com
> > >> To: grail69 at hotmail.com
> > >> CC: upstart-devel at lists.ubuntu.com
> > >> Subject: Re: Process substitution into loop
> > >>
> > >> On Fri, Jun 10, 2011 at 03:53:15AM +0000, Grail Dane wrote:
> > >> > Just wondering, as I can't find by googling, if it is at all
> possible to
> > >> > do a processsubstitution into a while loop within an upstart script?
> > >>
> > >> > Example:
> > >> > while read -r DEVICE
> > >> > do
> > >> > ip link set dev $DEVICE up
> > >> > done< <(ip link | awk '/^[0-9]/ && !/UP/ && gsub(/:/,""){print $2})
> > You have an error in your script: it is missing the closing tick (see
> below).
> >
> > >>
> > >> > When issuing the start command on the script I get:
> > >> > /proc/self/fd/10: line 6: syntax error near unexpected '<'init:
> > >> > network-interfaces main process (1367) terminated with status
> 2start: Job
> > >> > failed to start Would appreciated if someone would identify if i
> have done
> > >> > something wrong or if this not a supported feature?
> > >>
> > >> The <() syntax is not part of the POSIX standard, it's a bash
> extension.
> > >> Upstart uses /bin/sh to interpret scripts, as is customary; chances
> are
> > >> you're running on a system where /bin/sh is not bash, and as a result
> this
> > >
> > > Actually /bin/sh is a symbolic link to bash on my system. Is there
> anyway to have bash as the
> > > shell used?
> >
> > script
> > /bin/bash <<EOT
> > while read -r DEVICE
> > do
> > echo "DEBUG: ip link set dev $DEVICE up" > /tmp/grail.log
> > done < <(ip link | awk '/^[0-9]/ && !/UP/ && gsub(/:/,""){print $2}')
> > EOT
> > end script
> >
> > Also, just for you :)...
> >
> > http://upstart.ubuntu.com/cookbook/#changing-the-default-shell
> >
> > Regards,
> >
> > James.
> >
> > >
> > >> syntax is not supported.
> > >>
> > >> A supported syntax would be:
> > >>
> > >> ip link | awk '/^[0-9]/ && !/UP/ && gsub(/:/,""){print $2}' |
> > >> while read -r DEVICE
> > >> do
> > >> ip link set dev $DEVICE up
> > >> done
> > >>
> > >> --
> > >> Steve Langasek Give me a lever long enough and a Free OS
> > >> Debian Developer to set it on, and I can move the world.
> > >> Ubuntu Developer http://www.debian.org/
> > >> slangasek at ubuntu.com vorlon at debian.org
> > >
> >
>
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